Cramp a mystery to Murray
Andy Murray was shocked to find himself battling a cramping crisis in his first round victory over Robin Haase at the US Open.
The British No 1 had muscles seize up in several different parts of his body but still managed to see out a 6-3 7-6 (8-6) 1-6 7-5 win against the Dutchman.
The temperatures at Flushing Meadows were hot but not extreme and Murray says he did not expect suffer such physical problems in the circumstances.
"I felt extremely good before the match, and I did train very, very hard to get ready for the tournament," he said.
"For me it was unexpected, and therefore quite difficult mentally to deal with. Sometimes it can happen in one area of your body but when it starts to go everywhere, you don't know exactly where it's going to creep up next.
"When you stretch one muscle, something else then cramps, too. It was tough and very unexpected, especially after an hour and a half.
"So it's unlikely, I would say, that it's down to poor physical condition, because I have trained and played matches. I don't know if it's something I have done in the last few days that's been wrong or not, but I need to try and find out why.
"It's not the worst I have ever felt, but it's the worst I have ever felt after an hour and a half of a tennis match. That's what was worrying about it, is it came after such a short time."
Murray could offer no real explanation of what might have caused the cramp other than to guess it may have something to do with his food and fluid intake.
The match started earlier than expected because of a very quick women's match and Haase admitted he had had to rush his preparation, but Murray insisted that was not the case for him.
He added: "Sometimes nerves can bring it on. I certainly wasn't nervous at the beginning of the third set after just winning a tough second set.
"I didn't feel incredibly tired or anything. It just happened. The fact that it was the whole body would suggest that maybe it was something to do with my eating or drinking, because if it's through fatigue in one part of your body then that would probably be down to conditioning.
"But cramping in my left forearm? I mean, I didn't use my left forearm a whole lot today compared with other parts of my body."