NEW YORK -- As the clock ticked past midnight into Thursday morning, Stan Wawrinka and Juan Martin del Potro were just starting the third set.
At 1 a.m. ET, the fans of del Potro tried to lift his sagging spirits by singing the "Ole, Ole, Ole" soccer song. Seventeen minutes later, there was a rousing encore. It made a certain degree of sense that the last of the US Open quarterfinals would be a grudging, grueling affair.
Before a thinning but enthusiastic crowd on Arthur Ashe Stadium, Wawrinka and del Potro traded elegant punches until 1:20 a.m.
In the end, Wawrinka simply wore down del Potro, 7-6 (5), 4-6, 6-3, 6-2.
"Yeah, it was [a] crazy atmosphere, really late match," Wawrinka said in his on-court interview. "Thank you everybody for staying so late.
"I'm really happy to have won that match."
It was the second-latest-ending match of the tournament, following the Madison Keys-Alison Riske contest on the first night that ended at 1:48 a.m.
The match lasted 3 hours, 13 minutes, and both players had visits by the ATP trainer on two occasions.
The No. 3-seeded Wawrinka next plays No. 6 seed Kei Nishikori, who beat No. 2 Andy Murray earlier in five sets, in a Friday semifinal.
And so, after four harrowing wrist surgeries and a blazing comeback, the massively popular del Potro is out of the draw. Back in February, he was ranked outside the ATP World Tour's top 1,000. Here, up to No. 142, he became the lowest-ranked player to reach a US Open quarter since Jimmy Connors (No. 174) 25 years ago at the age of 39.
Now, del Potro will go home to Argentina with a top-65 ranking and a silver medal in singles from his trip to the Olympics in Rio de Janeiro. He was trying to beat a top-five player for the fourth time in five tries, a streak that includes a second-round win over Wawrinka at Wimbledon.
Wawrinka, 31, is carrying the flag here for Switzerland with 17-time Grand Slam singles winner Roger Federer absent from the US Open for the first time this century.
This is Wawrinka's second consecutive US Open semifinal appearance and third in four years. Wawrinka is into his seventh major semifinal since reaching his first here three years ago -- all past his 28th birthday.