Kei Nishikori of Japan returns a shot to Andy Murray of Great Britain during their Men's Singles Quarterfinal match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Mike Hewitt/Getty Images)
US Open: Day 10
Juan Martin del Potro of Argentina reacts as the crowd shouts his name during his US Open Men's Singles match against Stan Wawrinka of Switzerland at the USTA Billie Jean King National Tennis Center in New York on September 5, 2016. (Photo by Kena Betancur/AFP/Getty Images)
US Open: Day 10
Stan Wawrinka of Switzerland celebrates defeating Juan Martin del Potro of Argentina during their Men's Singles Quarterfinals Match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)
US Open: Day 10
Juan Martin del Potro of Argentina reacts against Stan Wawrinka of Switzerland during their Men's Singles Quarterfinals Match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Mike Hewitt/Getty Images)
US Open: Day 10
Stan Wawrinka of Switzerland hits a return to Juan Martin del Potro of Argentina during their 2016 US Open Men's Singles match at the USTA Billie Jean King National Tennis Center in New York on September 7, 2016. (Photo by Eduardo Munoz Alvarez/AFP/Getty Images)
US Open: Day 10
Stan Wawrinka of Switzerland awaits the serve from Juan Martin del Potro of Argentina during their US Open Men's Singles match at the USTA Billie Jean King National Tennis Center in New York on September 5, 2016. (Photo by Kena Betancur/AFP/Getty Images)
US Open: Day 10
Simona Halep of Romania falls as she plays against Serena Williams of United States during their 2016 US Open Women's Singles match at the USTA Billie Jean King National Tennis Center in New York on September 7, 2016. (Photo by Kena Betancur/AFP/Getty Images)
2016 US Open - Day 10
Serena Williams of the United States celebrates defeating Simona Halep of Romania during their Women's Singles Quarterfinals Match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)
US Open: Day 10
Serena Williams of United States hits a return against Simona Halep of Romania during their 2016 US Open Women's Singles match at the USTA Billie Jean King National Tennis Center in New York on September 7, 2016. (Photo by Kena Betancur/AFP/Getty Images)
TEN-US-OPEN-DEL-POTRO-WAWRINKA
Juan Martin del Potro of Argentina touches the head of the umpire as he plays against Stan Wawrinka of Switzerland during their US Open Men's Singles match at the USTA Billie Jean King National Tennis Center in New York on September 5, 2016. (Photo by Kena Betancur/AFP/Getty Images)
TEN-US-OPEN-WAWRINKA-DEL-POTRO
Juan Martin del Potro of Argentina serves to Stan Wawrinka of Switzerland during their 2016 US Open Men's Singles match at the USTA Billie Jean King National Tennis Center in New York on September 7, 2016. (Photo by Kena Betancur/AFP/Getty Images)
Tony Bennett At US Open
Singer Tony Bennett attends the Women's Singles Quarterfinals Match between Simona Halep of Romania and Serena Williams of the United States on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Mike Hewitt/Getty Images)
US Open: Day 10
Serena Williams of the United States serves to Simona Halep of Romania during their Women's Singles Quarterfinals Match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Mike Hewitt/Getty Images)
2016 US Open - Day 10
Serena Williams of the United States reacts against Simona Halep of Romania during their Women's Singles Quarterfinals Match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)
2016 US Open - Day 10
Simona Halep of Romania returns a shot to Serena Williams of the United States during their Women's Singles Quarterfinals Match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Mike Hewitt/Getty Images)
US Open: Day 10
Simona Halep of Romania gestures as she plays against Serena Williams of United States during their 2016 US Open Women's Singles match at the USTA Billie Jean King National Tennis Center in New York on September 7, 2016. (Photo by Kena Betancur/AFP/Getty Images)
2016 US Open - Day 10
Simona Halep of Romania reacts against Serena Williams of the United States during their Women's Singles Quarterfinals Match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)
US Open: Day 10
Serena Williams of the United States returns a shot to Simona Halep of Romania during their Women's Singles Quarterfinals Match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)
US Open: Day 10
Kei Nishikori of Japan celebrates after defeating Andy Murray of Great Britain during their Men's Singles Quarterfinal match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Alex Goodlett/Getty Images)
US Open: Day 10
Andy Murray of Britain reacts after losing a game against Kei Nishikori of Japan during their 2016 US Open Mens Singles quarterfinal match at the USTA Billie Jean King National Tennis Center in New York on September 7, 2016. (Photo by Jewel Samad/AFP/Getty Images)
US Open: Day 10
Andy Murray of Great Britain reacts against Kei Nishikori of Japan during their Men's Singles Quarterfinal match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Mike Hewitt/Getty Images)
US Open: Day 10
Kei Nishikori of Japan serves to Andy Murray of Great Britain during their 2016 US Open Men's Singles quarterfinals match at the USTA Billie Jean King National Tennis Center on September 7, 2016 in New York. (Photo by Don Emmert/AFP/Getty Images)
US Open: Day 10
Andy Murray of Great Britain returns a shot to Kei Nishikori of Japan during their Men's Singles Quarterfinal match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Al Bello/Getty Images)
US Open: Day 10
Kei Nishikori of Japan returns a shot to Andy Murray of Great Britain during their Men's Singles Quarterfinal match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Mike Hewitt/Getty Images)
US Open: Day 10
Ana Konjuh of Croatia serves to Karolina Pliskova of the Czech Republic during their Women's Singles Quarterfinal match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)
US Open: Day 10
Karolina Pliskova of the Czech Republic reacts against Ana Konjuh of Croatia during their Women's Singles Quarterfinal match on Day Ten of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 7, 2016 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Elsa/Getty Images)
TEN-US OPEN-PLISKOVA-KONJUH
Karolina Pliskova of Czech Republic serves against Ana Konjuh of Croatia during their 2016 US Open Womens Singles quarterfinal match at the USTA Billie Jean King National Tennis Center in New York on September 7, 2016. (Photo by Jewel Samad/AFP/Getty Images)
US Open: Day 10
Karolina Pliskova of Czech Republic hits a return against Ana Konjuh of Croatia during their 2016 US Open Womens Singles quarterfinal match at the USTA Billie Jean King National Tennis Center in New York on September 7, 2016. (Photo by Jewel Samad/AFP/Getty Images)
TEN-US OPEN-PLISKOVA-KONJUH
Ana Konjuh of Croatia hits a return against Karolina Pliskova of Czech Republic during their 2016 US Open Womens Singles quarterfinal match at the USTA Billie Jean King National Tennis Center in New York on September 7, 2016. (Photo by Jewel Samad/AFP/Getty Images)
