NEW YORK — John Isner's career fittingly ended with a final-set tiebreaker.

Isner put a volley into the net to end the match and what he had announced would be his final singles tournament, falling in the US Open second round to fellow American Michael Mmoh 3-6, 4-6, 7-6 (3), 6-4, 7-6 (7).

"It's tough. I like to think I work as hard as I can," Isner told a Grandstand crowd that erupted in cheers as he trailed off into tears.

The 38-year-old Isner, who needed a wild card to get into the draw at Flushing Meadows, blasted 48 aces and won 86% of his first-serve points in a match that also included 63 unforced errors. Several times, the 6-foot-10 (2.08-meter) Isner fell to the ground while diving to make volleys.

Isner reached a career-best ranking of No. 8 in 2018, shortly after reaching the semifinals at Wimbledon. He won 16 singles titles and hit 14,470 aces, an ATP Tour record. That includes 113 in the longest match in tennis history, a first-round Wimbledon win against Nicolas Mahut in 2010 that lasted 11 hours, 5 minutes and ended at 70-68 in the fifth set.

Next up for the 89th-ranked Mmoh will be Jack Draper, who upset an apparently ailing Hubert Hurkacz 6-2, 6-4, 7-5, extending his return to the tour after being out more than two months with a shoulder injury.

Draper, a 21-year Brit who only came back to the tour in early August, showed no signs of injury with strong serves and groundstrokes, while Hurkacz appeared listless at times and called the courtside medics over during a changeover in the final set.

It dashed the hopes of the 17th seed from Poland, who came into the US Open after a strong semifinal showing at the tune-up event in Cincinnati when he had a match point against No. 1 Carlos Alcaraz before eventually losing in three sets.

On the women's side, second-seeded Aryna Sabalenka had little trouble with Briton Jodie Burrage in a 6-2, 6-3 victory in a little more than an hour. She advances to a third-round matchup against Clara Burel of France, who beat No. 25 Karolina Pliskova 6-4, 6-2. American Madison Keys, the No. 17 seed, also advanced with a 6-1, 6-2 victory over Yanina Wickmayer of Belgium.

Elsewhere, sixth-seeded Jannik Sinner advanced to the third round with a 6-4, 6-2, 6-4 victory over fellow Italian Lorenzo Sonego.

Sinner has never lost to an Italian, improving to 10-0 against his countrymen. He's seeking at deep run at Flushing Meadows after reaching the semifinals at Wimbledon this year and the quarterfinals at last year's US Open, losing to Alcaraz in a five-set marathon after holding a match point.

"I felt now my game has improved a little bit and developed," said the 22-year-old Sinner, who won 89% of his first-serve points and was successful in 22 of 25 trips to the net.

"Physically, I'm good and let's see what's coming." Alexander Zverev, the No. 12 seed, downed fellow German Daniel Altmaier 7-6 (1), 3-6, 6-4, 6-3 on his return to outer Court 17.

Zverev was among several players who noticed a scent of marijuana on the court in the first round, describing it as smelling like "Snoop Dogg's living room." "I think it will stay the weed court for the tournament," he said Thursday.

For Zverev, a US Open finalist in 2020, it marked his fifth straight advance to the tournament's third round. He will face No. 19 seed Grigor Dimitrov, who downed Andy Murray in a convincing 6-3, 6-4, 6-1 victory in Arthur Ashe Stadium that included 45 unforced errors from the British three-time Grand Slam champion.

Later in night matches on Ashe, defending champion Alcaraz takes on Lloyd Harris, a South African who reached the quarterfinals at Flushing Meadows in 2021, and No. 3 Jessica Pegula faces Patricia Maria Tig.

AP