Simone Bolelli of Italy serves against Tommy Robredo of Spain during their men's singles second round match on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Al Bello/Getty Images)
2014 US Open - Day 4
Milos Raonic of Canada returns a shot against Peter Gojowczyk of Germany on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Alex Goodlett/Getty Images)
2014 US Open - Day 4
Borna Coric of Croatia returns a shot against Victor Estrella Burgos of the Dominican Republic on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Matthew Stockman/Getty Images)
2014 US Open - Day 4
Tommy Robredo of Spain serves against Simone Bolelli of Italy during their men's singles second round match on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014.(Photo by Al Bello/Getty Images)
2014 US Open - Day 4
Simone Bolelli of Italy argues a call with the chair umpire as Tommy Robredo (L) of Spain looks on during their men's singles second round match on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Al Bello/Getty Images)
2014 US Open - Day 4
Fans of Andy Murray of Great Britain cheer as he plays against Matthias Bachinger of Germany on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Julian Finney/Getty Images)
2014 US Open - Day 4
Serena Williams (L) and Venus Williams of the United States play their women's doubles match against Timea Babos of Hungary and Kristina Mladenovic of France on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Streeter Lecka/Getty Images)
2014 US Open - Day 4
Ekaterina Makarova of Russia returns a shot against Polona Hercog of Slovenia on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Alex Goodlett/Getty Images)
2014 US Open - Day 4
The sun sets in the distance as fountains are seen in the south plaza near Arthur Ashe Stadium on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Chris Trotman/Getty Images for USTA)
2014 US Open - Day 4
Andy Murray of Great Britain returns a shot against Matthias Bachinger of Germany on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Julian Finney/Getty Images)
2014 US Open - Day 4
Billie Jean King waves to the crowd on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Julian Finney/Getty Images)
2014 US Open - Day 4
Eugenie Bouchard of Canada serves against Sorana Cirstea of Romania on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Chris Trotman/Getty Images for USTA)
2014 US Open - Day 4
Milos Raonic of Canada serves against Peter Gojowczyk of Germany on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Streeter Lecka/Getty Images)
2014 US Open - Day 4
Eugenie Bouchard of Canada celebrates match point against Sorana Cirstea of Romania on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Streeter Lecka/Getty Images)
2014 US Open - Day 4
Catherine 'CiCi' Bellis of the United States celebrates a point against Zarina Diyas of Kazakhstan during their women's singles second round match on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014. (Photo by Matthew Stockman/Getty Images)
