Top seeds Serena, Djokovic limp into Flushing

Smashing tennis stars Serena and Venus Williams already have two US Open’s women’s doubles titles (along with many singles crowns) — but are they any good at “Virtua Tennis”? The sisters gave the Sega simulation game a try in Midtown leading up to the start of the tourney in Queens.

Breaking down the Open draw /

The two U.S. Open favorites are slumping and banged up heading into Flushing. Top-seeded Serena Williams said the shoulder injury that forced her to withdraw from a key Open tuneup in Cincinnati is better, but hardly 100 percent.

Defending Open champion and No. 1 men’s seed Novak Djokovic revealed a right-wrist injury he said occurred during the Rio Olympics and added he has been doing “electricity treatments” to speed the healing.

“The wrist hasn’t been in ideal state for the last 3 ¹/2 weeks, but I’m doing everything in my power with obviously the medical team to make sure that I’m as close to 100 percent as possible during the course of this tournament,” said Djokovic, who won the Australian and French Opens this year before petering out at Wimbledon and the Olympics.

Djokovic lost in the first round in Rio to Juan Martin del Potro, a player who has had wrist issues derail his once-glittering career.

“It happened just a few days be- fore the start of the tournament [in Rio],” Djokovic said. “I did experience this for the first time in my career. Never had this particular wrist injury before.”

Williams won’t exactly give herself a clean bill of health and was curt on the subject. The shoulder issue directly affected her menacing serve in the Olympics, where she lost in the third round to Ukraine’s Elina Svitolina.

“I have not played a lot, I haven’t practiced a lot, but I’m just now starting to feel a little better,” said Williams, known for her marathon practice sessions with coach Patrick Mouratoglou. “Hopefully just every day I will keep going higher.”

Williams is attempting to set two new milestones, topping Chris Evert for most Open titles with a seventh and surpassing Steffi Graf for most Grand Slam singles titles in the open era with 23.

“I think usually I prefer to play more coming into the final Grand Slam of the year, but I really don’t think — there is nothing we can do about it,” Williams said. “You just have to make the best of every single opportunity. That’s all I can do now.”