Olympic gold medalist Alexander Zverev ran his winning streak to 12 matches by beating Sam Querrey 6-4, 7-5, 6-2 on Tuesday in the first round of the U.S. Open.

The No. 4 seed from Germany stopped Novak Djokovic's quest for a Golden Slam in Tokyo and is among the players with the best chance to prevent a Grand Slam in New York.

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Zverev, the runner-up here last year, followed up his victory in the Olympics by winning the hard-court title at Cincinnati.

"I’ve won two tournaments, I’m on a 12-match winning streak," Zverev said. "I hope I can keep the level up and maybe even play better, because to beat Novak here is going to be an extremely difficult task."

Djokovic plays his first-round match Tuesday night against Danish qualifier Holger Rune. The top-ranked Djokovic is trying to become the first men's player since 1969 to win all four Grand Slam tournaments in one year.

Djokovic would break a tie with Roger Federer and Rafael Nadal for most major titles among men if he wins the tournament. They all have 20.

The No. 1 seed on the women's side was also in action, with Ash Barty holding off 2010 U.S. Open runner-up Vera Zvonareva 6-1, 7-6 (7).

Zverev came as close as could be to winning his first major title last year in Flushing Meadows. He took the first two sets against Dominic Thiem before losing in a fifth-set tiebreaker, becoming the first player to lose the U.S. Open final after winning the first two sets since Frederick Schroeder in 1949.

He certainly looks capable of finishing the job this time. He stormed past Djokovic in the final two sets of their Olympic semifinal and then rolled past Karen Khachanov in the final.

He followed that with his win at Cincinnati, where he beat Stefanos Tsitsipas and Andrey Rublev, both among the top five seeds in New York. Thiem is not playing this year because of a wrist injury, one of several big names sidelined.

Zverev is one of three men, along with Djokovic and Casper Ruud, with four titles this season. But he knows the tournaments that Djokovic won make him the obvious pick in New York.

"If a guy wins three majors in the same year and then is at the U.S. Open, you have to give him the favorite card," Zverev said. "Because if not now, then when?"

Barty won Wimbledon for her second major title and now is back in New York after remaining in Australia last year when the event was played with no fans because of the coronavirus pandemic.

"I was disappointed not to be able to come and play last year but I think playing here this year with fans makes it all the better," Barty said.

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No. 4 seed Karolina Pliskova, the 2016 U.S. Open runner-up who lost to Barty in the Wimbledon final, beat American teenager Caty McNally 6-3, 6-4. Belinda Bencic, the women's Olympic gold medalist seeded 11th, beat Arantxa Rus 6-4, 6-4, and No. 17 seed Maria Sakkari topped Marta Kostyuk 6-4, 6-3.

Reilly Opelka, the No. 22-seeded man, swept past Soonwoo Kwon and fellow American Mackenzie McDonald upset No. 27 seed David Goffin 6-2, 7-5, 6-3. But Sebastian Korda, another promising young American, was eliminated when he retired against Nikoloz Basilashvili early in the second set.

Khachanov, the No. 25 seed, was knocked off by Lloyd Harris 6-4, 1-6, 4-6, 6-3, 6-2.