The shaky serving. The consecutive netted forehands that handed over a key break. The inability to take control against an opponent ranked 192nd.

And then, on the way to a 6-2, 4-6, 7-6 (1) victory over Jack Sock at the Citi Open over more than three hours Wednesday night, there were moments when Nadal seemed every bit the 20-time Grand Slam champion who drew a full house announced at 7,500 merely by making his debut at the hard-court tournament.

''The match wasn't easy," Nadal said. "I started to suffer a little bit too much.'' The highlight was a back-to-the-net, between-the-legs bit of magic in the first set that prompted Nadal to punch the air and prompted his fans to stand and roar. The court coverage on that effort, and when he smacked an on-the-run winner off a drop shot by Sock in the tiebreaker, at least, hid any apparent issues stemming from the foot injury Nadal recently revealed was part of why he sat out Wimbledon and the Tokyo Olympics and went three weeks without lifting a racket.

The pair of lefty forehand winners he snapped off to earn a set point that he then converted with a return winner to take the opener was among the good. So was his impeccable form in the tiebreaker. The first-serve percentage of 47 in the opening set and an inability to collect so much as a single break chance in the second were among the bad.

Those sorts of miscues "open the door to a player like him," Nadal said about Sock, against whom he's now 6-0.

''I just need to have a little bit less pain in the foot, honestly," Nadal said. ''That's the truth." There was a lot of up-and-down play by the 35-year-old Spaniard, which Nadal himself suggested could happen. That makes sense, given that he last played a point that mattered in June, during a loss to Novak Djokovic in the semifinals of the French Open, an event Nadal has won 13 times.

After that, Nadal said his body needed to rest and recover from the grueling clay-court circuit. In the meantime, Djokovic pulled even with Nadal and Roger Federer at 20 major championships apiece, so the Big Three share the men's record heading into the U.S. Open, where play begins Aug. 30.

If getting match-ready ahead of the trip to Flushing Meadows is of primary importance, Nadal did get an opportunity to try to shake off some rust against Sock, an American who is a former member of the top 10 in singles and owner of three Grand Slam titles in men's doubles.

After getting broken to trail 4-3 in the second set, then again to go down 1-0 in the third, a deficit that would reach 3-1, Nadal reverted to his best self.

He held without trouble, then broke to 3-all by whipping a forehand to close a 16-stroke exchange before sprinting to reach a drop shot and extend a point he would win — and mark with a yell of "Vamos!" and fist pumps — when Sock netted his response.

Suddenly, with the help of an over-the-shoulder flicked volley, Nadal held again and now led 4-3. He was simply far better at the very end.

''You need matches like this to be fitter after months without competing,'' Nadal said.

On Thursday, he will meet 14th-seeded Lloyd Harris, a South African who advanced when his opponent, Tennys Sandgren of the U.S., stopped playing because of the rib pain.

Earlier, No. 6 seed Dan Evans lost his first match since testing positive for COVID-19 last month and missing the Olympics. Evans was beaten 7-6 (1), 6-0 by Brandon Nakashima of the U.S.

Other seeds exiting Wednesday: No. 3 Alex de Minaur, No. 4 Grigor Dimitrov, No. 9 Alexander Bublik, No. 10 Taylor Fritz, and No. 13 Benoit Paire.

Nadal nearly joined them on the way out. Pushed to the brink, he pulled through.