Caroline Wozniacki reached the final of the US Open here last night but not in the manner she would have wanted. Shuai Peng, the Dane's semi-final opponent, left Arthur Ashe Stadium in a wheelchair when she retired in the second set after an hour and 53 minutes because of what appeared to be cramp and heat exhaustion. The 28-year-old Chinese was trailing 7-6, 4-3 at the time.
Peng had left the court in controversial circumstances earlier in the same game because of what seemed to be severe cramping in her legs. Struggling to cope with the 29C heat and 65 per cent humidity, Peng was barely able to stand up without support. When she returned 10 minutes later, the world No 39 played only five more points before falling to her knees. Peng, who had heart surgery when she was 12, was clearly in agony and was forced to retire.
Tournament rules state that when players are injured they can seek assessment of their condition and take a medical time-out for treatment. However, the same rules do not apply to cramp. John McEnroe described the decision to allow her to leave the court as "absurd", adding: "She should never have been allowed back on court for a host of reasons."
David Brewer, the tournament director, defended the decision, saying Peng had received "an off-court medical assessment". He added: "When a player is in stress she is allowed to be evaluated by medical personnel. There is no time limit. You are allowed a reasonable amount of time."
Wozniacki, who in tomorrow's final will play the winner of last night's later meeting between Serena Williams and Ekaterina Makarova, said the conditions had been "really tough". She felt sorry for her opponent, though she was delighted to be through to her second Grand Slam final. She played in her first on this court five years ago, losing to Kim Clijsters. "It's incredible to be back in the final," Wozniacki said. "I've got goosebumps right now."
The men's semi-finals will be played back-to-back this afternoon, beginning with Novak Djokovic against Kei Nishikori at midday (5pm BST), followed by Roger Federer's meeting with Marin Cilic. It will be Federer's ninth semi-final here and his 36th in all Grand Slam tournaments.
However, Federer very nearly lost in the quarter-finals. The Swiss lost the first two sets against Gaël Monfils and had to save two match points before beating the Frenchman 4-6, 3-6, 6-4, 7-5, 6-2, in front of a captivated crowd in Arthur Ashe Stadium. It was the ninth time in his career that Federer has won a match from two sets down.
"It's just unbelievable to win matches like this at Slams," Federer said. "I have won other big ones in other places, but over best-of-five, saving match points against Gael in that atmosphere tonight, it's definitely very special.
"I'm not sure I have ever saved match point before in a Slam. I'm unbelievably happy that it was today, because I knew I could play better after the first couple of sets."
