Serena rallies past Pliskova to move into semisfinals

Stephens said she had been battling a cold, but her biggest problem Tuesday might have been her serve. The No. 3 seed was broken five times in the 84-minute match.

John Isner’s bid to become the first American man in a dozen years to get to the final four at Flushing Meadows ended Tuesday with a 6-7 (5), 6-3, 7-6 (4), 6-2 loss in Arthur Ashe Stadium to No. 3 seed Juan Martin del Potro, the Argentine who won the 2009 championship.

The temperature, more than 90 degrees made things uncomfortable across the Serena Williams celebrates after defeating Karolina Pliskova during Tuesday’s quarterfinal match at the U.S. Open in New York.

Tribune News Service 3½-hour match. So did the humidity, at about 50 percent. Those kinds of conditions were a problem for Roger Federer when he was upset by 55th-ranked John Millman a night earlier, and Isner had all kinds of trouble too – certainly more than del Potro did.

“Whatever the humidity is on outer courts or in the city, I think it’s amplified on center court,” Isner said. “It’s just very difficult to deal with. I have never seen Roger sweat, ever. If he’s sweating a lot and has to change clothes, then you know it’s pretty humid out there.”

Del Potro will face No. 1 seed Rafael Nadal in the semifinals on Friday after Nadal beat No. 9 Dominic Thiem in a fiveset thriller on Tuesday evening, 0-6, 6-4, 7-5, 6-7(4), 7-6(5).

Thiem was red-hot to start, breaking Nadal in the very first game of the match, and he didn’t slow down, at least through a first set where he blanked the “King of Clay”, 6-0. But Nadal narrowed the gap quickly in the second set, and took over the match, though it was always close.

Tuesday’s match was the first time they’ve ever faced off professionally on a surface other than clay. Nadal led the series, 7-3, going into the match, which is significant for a number of reasons. The biggest is that beating Nadal on clay is simply the toughest accomplishment in tennis, and Thiem, also a clay court specialist, did extremely well to earn three wins off of him, including in Madrid earlier this year.

His match against Nadal on Tuesday was impressive, especially the opening set, but Nadal once again proved to be too much in the long run.