US Open | Nishikori ousts Murray ; Serena survives Simona scare

Andy Murray had earlier claimed to be having sleepless nights against the Japanese World No. 7 ahead of their quarterfinal encounter. Murray had dominated the head-to-head record against Nishikori beating him seven times in eight meetings so far, and when the duo faced each other in the semis of the Rio Olympics, where the Brit defeated the Japanese star 6-1, 6-4. The only time Nishikori had defeated Murray was back in 2014 at the ATP World Tour Finals. Yet, Murray appeared to have a bit of prescience about how the night was going to end.

However, a return to his error-prone ways cost Nishikori the third set even as the opponents managed to break each other frequently. Despite winning the set 6-4, Murray was yet to find his rhythm and was merely coasting along – his serve was not booming, and his returns just less error-prone than Nishikori's.

Broken early in the fifth set to 0-2, Murray looked down and out. But he clawed his way back on the back of some errors from Nishikori to draw par at 2-2. But Murray double-faulted in the next to give a break to Nishikori to 2-3, but soon came back again to make it 4-4. At 5-5, when he needed to stay in the game the most, Murray double-faulted again – his second in the set and third overall – and Nishikori grabbed the chance to go up 6-5.

Serving for the match, the Japanese began with a doublefault of his own but managed to hold his nerves and win the match to enter the semifinal.

Murray said: “I wasn’t too disappointed. I’ve had a good few months. I’m sorry not to have won but there you go.”

Meanwhile, Serena Williams was tested for the first time at the Flushing Meadows this year. Her serve was broken for the first time in the tournament and she even lost a set, but eventually Serena defeated 2014 French Open runner-up and No. 5 seed Simona Halep 6-2, 4-6, 6-3 to reach the semi-finals.

But in the third, Serena broke Simona early on and wrapped up the set 6-3 to enter the semifinal.

Williams will play Czech 10th seed Karolina Pliskova in the semi-finals.

Although del Potro took an early 3-0 and 4-1 lead in the first set, it was Wawrinka who caught the eye with his impressive winners crowded out, however, by numerous unforced errors. There was a minor scare when Stan called for the trainer at this point, but it was merely precautionary as he showed soon. Stan managed to draw par at 4-4 and enforced the tie-break despite some brilliant court coverage from the big Argentinian. Racing to a 3-0 lead in the tie-break, Stan managed to hold on and del Potro's netted forehand on set point gave him a 7-6 win.

The second set saw both neck-to-neck until midway - Stan banking on his backhand, while del Potro unleashed his fearsome forehand to the fullest. But del Potro broke the deadlock with a break to go 4-3 and took the second set.

It was Wawrinka all the way in the fourth as he took a 3-0 lead on the back of some lovely passing shots against a tired del Potro. Serving for the set at 5-2, Wawrinka brought up match point with a pin-point forehand. And then came the lovely Wawrinka backhand down the line to wrap up the proceedings at 6-2.

Asked what he did after that second set, Wawrinka said, "I tried to keep him playing more balls and kept the ball to his backhand".