NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States walks on court prior to the start of her Women's Singles Fourth Round match against Madison Keys of the United States on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States walks on court prior to the start of her Women's Singles Fourth Round match against Madison Keys of the United States on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States walks on court prior to the start of her Women's Singles Fourth Round match against Madison Keys of the United States on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
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on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City.
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States returns a shot to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States returns a shot to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States returns a shot to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
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on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City.
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States returns a shot to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)
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on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City.
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on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City.
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on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City.
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States celebrates after defeating Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)
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on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City.
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States celebrates after defeating Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States returns a shot to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Matthew Stockman/Getty Images)
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on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City.
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on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City.
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States celebrates after defeating Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: (L-R) Serena Williams of the United States shakes hands with Madison Keys of the United States after their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)
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on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City.
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States signs autographs after defeating Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: (L-R) Serena Williams of the United States touches Madison Keys of the United States after their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States celebrates after defeating Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States celebrates after defeating Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States returns a shot to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States returns a shot to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: A shoe detail of Serena Williams of the United States as she serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States returns a shot to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States returns a shot to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States celebrates after defeating Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: (L-R) Serena Williams of the United States shakes hands with Madison Keys of the United States after their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States returns a shot to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States returns a shot to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States returns a shot to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
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on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City.
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States reacts against Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States reacts against Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 US Open - Day Seven
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 U.S. Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Chris Trotman/Getty Images for the USTA)
2015 US Open - Day Seven
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 U.S. Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Chris Trotman/Getty Images for the USTA)
2015 US Open - Day Seven
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 U.S. Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Chris Trotman/Getty Images for the USTA)
2015 US Open - Day Seven
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 U.S. Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Chris Trotman/Getty Images for the USTA)
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during day seven of the 2015 U.S. Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City.
2015 US Open - Day Seven
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 U.S. Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Chris Trotman/Getty Images for the USTA)
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during day seven of the 2015 U.S. Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City.
2015 US Open - Day Seven
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States serves to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 U.S. Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Chris Trotman/Getty Images for the USTA)
2015 US Open - Day Seven
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States returns a shot to Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 U.S. Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Chris Trotman/Getty Images for the USTA)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States reacts against Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
2015 U.S. Open - Day 7
NEW YORK, NY - SEPTEMBER 06: Serena Williams of the United States reacts against Madison Keys of the United States during their Women's Singles Fourth Round match on Day Seven of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
