Andy Murray now knows that he can serve at severely reduced speed and contort himself into pained positions that bear more resemblance to modern dance than modern tennis and still win a match at the United States Open.

There may be some comfort in that. Tennis, after all, is about points, not style points. But what was far from reassuring for Murray, once a U.S. Open champion, was that he was cramping and suffering (and muttering) against Robin Haase after just two sets in this age of the men’s tennis marathon.

“It’s not the worst I have ever felt necessarily, but it’s the worst I have ever felt after an hour and a half of a tennis match,” he said after his 6-3, 7-6 (6), 1-6, 7-5 victory.