Andy Murray defied his own body and Dutch opponent Robin Haase to reach the second round of the US Open last night.

In conditions that were hot but not extreme, the Scot struggled badly with cramp during the last two sets but survived to win 6-3 7-6 (8/6) 1-6 7-5.

Haase, who was also troubled physically, served for the fourth set but could not take advantage of Murray’s discomfort.

It was another dramatic match on Louis Armstrong Stadium for Murray, who has endured some of his least comfortable moments in grand slams on Flushing Meadows’ second court.

The 27-year-old, who next meets German qualifier Matthias Bachinger, said: “I started cramping at the beginning of the third set.

“It was not particularly comfortable. I tried to hang around as best I could and managed to get through.

“I need to work out why that happened today because it shouldn’t happen after an hour and 45 minutes, even though it was hot.”

Second seed Simona Halep survived a scare by overtaking American wild card Danielle Collins 6-7 (2) 6-1 6-2.

The French Open finalist moves on to face Slovakian Jana Cepelova, a 2-6 7-5 6-1 winner over Spain’s Maria-Teresa Torro-Flor.

But the 22-year-old Romanian had a tricky time getting by Collins.

Down a break at 3-4, the 20-year-old American brought the set back on serve at 4-all and with her confidence growing she ran away with the decider by taking advantage of an erratic Halep.

That shock seemed to snap Halep who brought her groundstrokes under control to roar to victory.

Other result: V. Williams bt Date Krumm 2-6 6-3 6-3.