Venus Williams of the US reacts afer defeating Kimiko Date-Krumm of Japan during the 2014 US Open Tennis Championship at the USTA National Tennis Center in Flushing, Meadows, New York, USA, 25 August 2014. The US Open runs through Monday 08 September, a 15-day schedule. EPA/JUSTIN LANE

Sloane Stephens of the US hits a return to Annika Beck of Germany during the 2014 US Open Tennis Championship at the USTA National Tennis Center in Flushing, Meadows, New York, USA, 25 August 2014. The US Open runs through Monday 08 September, a 15-day schedule. EPA/JASON SZENES

Jo-Wilfried Tsonga of France hits a return to Juan Monaco of Argentina during the 2014 US Open Tennis Championship at the USTA National Tennis Center in Flushing, Meadows, New York, USA, 25 August 2014. The US Open runs through Monday 08 September, a 15-day schedule. EPA/JASON SZENES

Andy Murray of Great Britain reacts as he plays Robin Haase of the Netherlands during the 2014 US Open Tennis Championship at the USTA National Tennis Center in Flushing, Meadows, New York, USA, 25 August 2014. The US Open runs through Monday 08 September, a 15-day schedule. EPA/JASON SZENES

Daniela Hantuchova of Slovankia hits a return to Romina Oprandi of Switzerland during the 2014 US Open Tennis Championship at the USTA National Tennis Center in Flushing, Meadows, New York, USA, 25 August 2014. The US Open runs through Monday 08 September, a 15-day schedule. EPA/JOHN G. MABANGLO