US Open: Day 9

Roberta Vinci of Italy hits a return against Angeliue Kerber of Germany during their 2016 US Open Womens Singles quarterfinal match at the USTA Billie Jean King National Tennis Center in New York on September 6, 2016. (Photo by Jewel Samad/AFP/Getty Images)

US Open: Day 9

Angelique Kerber of Germany celebrates after defeating Roberta Vinci of Italy during their Women's Singles Quarterfinal Match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)

US Open: Day 9

Angelique Kerber of Germany returns a shot to Roberta Vinci of Italy during their Women's Singles Quarterfinal Match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)

US Open: Day 9

Angelique Kerber of Germany (left) shakes hands with Roberta Vinci of Italy after their Women's Singles Quarterfinal Match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)

US Open: Day 9

Roberta Vinci of Italy waves to the crowd after being defeated by Angelique Kerber of Germany during their Women's Singles Quarterfinal Match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)

US Open: Day 9

Lucas Pouille of France hits a return against his compatriot Gael Monfils during their 2016 US Open Mens Singles quarterfinal match at the USTA Billie Jean King National Tennis Center in New York on September 6, 2016. (Photo by Jewel Samad/AFP/Getty Images)

US Open: Day 9

Gael Monfils of France sits under an umbrella as rain falls during his Men's Singles Quarterfinal Match against Lucas Pouille of France on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)

US Open: Day 9

A general view as Gael Monfils of France plays against Lucas Pouille of France during their Men's Singles Quarterfinal Match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Al Bello/Getty Images)

US Open: Day 9

Gael Monfils (R) of France greets his compatriot Lucas Pouille at the net after defeating him in their 2016 US Open Mens Singles quarterfinal match at the USTA Billie Jean King National Tennis Center in New York on September 6, 2016. / AFP / TIMOTHY A. CLARY (Photo credit should read TIMOTHY A. CLARY/AFP/Getty Images)

US Open: Day 9

Gael Monfils of France returns a shot to Lucas Pouille of France during their Men's Singles Quarterfinal Match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)

US Open: Day 9

Young fans wait for autographs from Gael Monfils of France after defeating Lucas Pouille of France in their Men's Singles Quarterfinal Match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)

US Open: Day 9

Angelique Kerber of Germany reacts against Roberta Vinci of Italy during their Women's Singles Quarterfinal Matchon Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Queens borough of New York City. (Photo by Mike Stobe/Getty Images for USTA)

US Open: Day 9

Angelique Kerber of Germany returns a shot against Roberta Vinci of Italy during their Women's Singles Quarterfinal Matchon Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Queens borough of New York City. (Photo by Mike Stobe/Getty Images for USTA)

US Open: Day 9

Bob Bryan (R) and Mike Bryan of the United States celebrate during their Men's Doubles Quarterfinals Match against Feliciano Lopez and Marc Lopez on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)

US Open: Day 9

A general view as Bob Bryan and Mike Bryan of the United States play against against Feliciano Lopez and Marc Lopez of Spain during their Men's Doubles Quarterfinals Match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)

US Open: Day 9

Feliciano Lopez (L) and Marc Lopez of Spain walk from the court during a rain delay in their Men's Doubles Quarterfinals Match against Bob Bryan and Mike Bryan of the United States on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)

US Open: Day 9

Anastasija Sevastova of Lativa reacts against Caroline Wozniacki of Denmark during their Women's Singles Quarterfinals matchon Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)

US Open: Day 9

Caroline Wozniacki of Denmark returns a shot to Anastasija Sevastova of Lativa during their Women's Singles Quarterfinals match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)

Shaquille O'Neal At US Open

Shaquille O'Neal attends the US Open women's quarterfinals match between Caroline Wozniacki and Anastasija Sevastova on Sept. 6, 2016. (Photo by Alex Goodlett/Getty Images)

US Open: Day 9

Caroline Wozniacki of Denmark celebrates defeating Anastasija Sevastova of Lativa during their Women's Singles Quarterfinals match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)

US Open: Day 9

Caroline Wozniacki of Denmark celebrates defeating Anastasija Sevastova of Lativa during their Women's Singles Quarterfinals match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)

US Open: Day 9

Caroline Wozniacki of Denmark returns a shot to Anastasija Sevastova of Lativa during their Women's Singles Quarterfinals match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Michael Reaves/Getty Images)

US Open: Day 9

Caroline Wozniacki of Denmark serves to Anastasija Sevastova of Lativa during their Women's Singles Quarterfinals match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Michael Reaves/Getty Images)

Christine Taylor, Ben Stiller And Hugh Jackman At US Open

Actors I(from left) Christine Taylor, Ben Stiller and Hugh Jackman attend the men's singles quarterfinals match between Novak Djokovic and Jo-Wilfried Tsonga on Day 9 of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Michael Reaves/Getty Images)

US Open: Day 9

Novak Djokovic of Serbia hits a return against Jo-Wilfried Tsonga of France during their 2016 US Open Men's Singles match at the USTA Billie Jean King National Tennis Center in New York on September 6, 2016. (Photo by Kena Betancur/AFP/Getty Images)

US Open: Day 9

Jo-Wilfried Tsonga of France receives medical attention during his Men's Singles Quarterfinals match against Novak Djokovic of Serbia on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)

US Open: Day 9

Novak Djokovic of Serbia celebrates defeating Jo-Wilfried Tsonga of France during their Men's Singles Quarterfinals match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)

US Open: Day 9

Novak Djokovic of Serbia returns a shot to Jo-Wilfried Tsonga of France during their Men's Singles Quarterfinals match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Michael Reaves/Getty Images)

US Open: Day 9

Novak Djokovic of Serbia serves to Jo-Wilfried Tsonga of France during their Men's Singles Quarterfinals match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Queens borough of New York City. (Photo by Chris Trotman/Getty Images for USTA)

US Open: Day 9

Jo-Wilfried Tsonga of France waves after retiring due to injury after playing against Novak Djokovic of Serbia (left) in their 2016 US Open Men's Singles match at the USTA Billie Jean King National Tennis Center in New York on September 6, 2016. Defending champion Novak Djokovic reached his 10th successive US Open semi-final when Jo-Wilfried Tsonga retired from their quarter-final with a left knee injury while trailing 6-3, 6-2. (Photo by Kena Betancur/AFP/Getty Images)

US Open: Day 9

Novak Djokovic of Serbia celebrates defeating Jo-Wilfried Tsonga of France during their Men's Singles Quarterfinals match on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Michael Reaves/Getty Images)

Michael Bloomberg At US Open

Michael Bloomberg, former mayor of New York City (C), (L) Diana Taylor, and Georgina Bloomberg (R) attend the Men's Singles Quarterfinals match between Novak Djokovic of Serbia and Jo-Wilfried Tsonga of France on Day Nine of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)