Kei Nishikori, this year’s sixth seed and the runner-up at the 2014 Open, came back and stunned Murray, 1-6, 6-4, 4-6, 6-1, 7-5, in a thrilling, back-and-forth duel that was determined, at least one man thought, by the roof.
“I think definitely under the roof he was able to dictate more of the points,” Murray said.
Nishikori reached the semifinals at a major tournament for only the second time and will face the winner of Wednesday night’s match between No. 3 Stan Wawrinka and the wild card Juan Martín del Potro.
Nishikori, who had lost seven of his eight previous matches to Murray, has not always played to his potential. But the U.S. Open is becoming his favorite Grand Slam event.
“I love the crowd,” he said. “It makes me more motivated. It’s little bit different than other Grand Slams. It’s more loud, and it’s more like a big party on the court.”
Murray enjoyed that feeling when he took the title in 2012, but even after an outstanding summer in which he won the Wimbledon title and the gold medal at the Rio de Janeiro Olympics, he may wonder about this match. Was it really the closing of the roof that changed the conditions, or was it his preoccupation with it?