NEW YORK (AP) — Maybe, just maybe, Novak Djokovic and Roger Federer are feeling some lingering after-effects of their historic Wimbledon final last month.

For Djokovic, it’s in the form of a left shoulder that is hurting right now and probably contributed to slower-than-usual serves in the U.S. Open’s second round Wednesday night.

For Federer, it’s in the form of slow starts: He’s lost the opening set each of his first two matches at Flushing Meadows for the first time in 19 times he’s entered the Grand Slam tournament.

If they’re going to reprise their rivalry late next week in the semifinals, both will need to improve.

Djokovic was repeatedly visited by a trainer for shoulder massages at changeovers during a ragged 6-4, 7-6 (3), 6-1 victory over 56th-ranked Juan Ignacio Londero of Argentina. Djokovic is a righty, of course, but he uses his other hand both for ball tosses on serves and on his two-fisted backhand — and both were less effective for stretches.

“I was definitely tested. This is something I’ve been carrying for a quite a while now,” said Djokovic, who repeatedly shook his left arm between points while serving in his first-round match Monday and did that again this time. “It wasn’t easy playing with the pain and you have to fight and hope you get lucky with some shots.”

Even though he won for the 35th time in his past 36 Slam matches, including in a fifth-set tiebreaker against Federer at the All England Club on July 14, the Serb looked uncomfortable and went away for stretches, including trailing 3-0 in the second set.

Asked how he plans to prepare for his next match Friday, Djokovic replied with a laugh: “I’ll probably freeze my arm for 48 hours, not do anything with it, and then see what happens.”

Federer, meanwhile, is not about to start trying new tricks now, despite needing to come back twice already.

He got to the third round by beating Damir Dzumhur 3-6, 6-2, 6-3, 6-4 on an afternoon when rain postponed all but nine scheduled singles matches and every doubles contest.

Still, it’s not as if the guy is going to seek some sort of magic solution. Working up more of a sweat in the gym before heading to the court, say. Or playing an extra practice set.

What he chose to focus on, instead, is looking on the bright side: “Can only do better,” Federer said, “which is a great thing, moving forward.”

At a Flushing Meadows flush with surprises so far — half of the top 12 seeded men already were gone by the time Federer stepped into Arthur Ashe Stadium — he cleaned up his act quickly.

Indeed, Federer was one of the lucky ones who will stay on the usual play-one-day, get-a-day-off Grand Slam schedule. Only matches at Ashe or Louis Armstrong Stadium, the event’s two arenas with a retractable roof, were held.

That included a loss by two-time champion Venus Williams to No. 5 seed Elina Svitolina, and victories for No. 2 Ash Barty, No. 3 Karolina Pliskova and 2017 runner-up Madison Keys on the women’s side, and a win for No. 7 Kei Nishikori on the men’s.

The night program included Williams’ younger sister, Serena, against 17-year-old American Caty McNally.

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