NEW YORK (AFP) -- Third seed Daniil Medvedev strolled into the second round of the US Open with a quick-fire victory as world number one Carlos Alcaraz prepared to launch his title defense on Tuesday, Aug. 29.

Medvedev, the 2021 US Open champion, made a flying start with a 6-1, 6-1, 6-0 thrashing of Hungary's Attila Balazs in just 74 minutes on the Arthur Ashe Stadium court.

The Russian will face Australia's Christopher O'Connell in the second round on Thursday for a spot in the last 32.

"That's probably the fastest three-set match I played," Medvedev said after his swift demolition of Balazs.

"I'm looking forward to the next round... the goal is always to try to play better and better every match, because every match is going to be tougher and tougher.

"Let's see how the next one goes."

The 27-year-old from Moscow is on a collision course to meet Alcaraz in the semifinals in New York, a repeat of their Wimbledon clash in July. Alcaraz won that meeting in straight sets.

Alcaraz, 20, will open his US Open campaign with a night match later Tuesday against lowly ranked German Dominik Koepfer.

The Spaniard is aiming to become the first man to defend the US Open crown since 2008, when Roger Federer lifted the title for a fifth consecutive year.

Alcaraz went into this year's tournament as world number one, but will lose that ranking after the event following Novak Djokovic's imperious performance on Monday.

While Medvedev eased into the second round, compatriot Karen Khachanov -- a semifinalist at last year's US Open -- was on the wrong end of a first-round upset.

The 11th-seeded Russian was bounced out in straight sets by American world No. 89 Michael Mmoh, losing 6-2, 6-4, 6-2.

Germany's 12th seed Alexander Zverev, a beaten finalist at Flushing Meadows in 2020, never looked in danger of following Khachanov out of the tournament, registering a 6-4, 6-4, 6-4 win over Australia's Aleksandar Vukic.

Ailing Jabeur advances

In the women's draw meanwhile another semifinalist from 2022 also made an early exit, with French seventh seed Caroline Garcia slumping to a 6-4, 6-1 reverse against Chinese qualifier Wang Yafan.

Tunisia's Ons Jabeur, desperate to land her first Grand Slam title after losing in three major championship finals in 2022 and 2023, survived a medical scare before scraping past Colombia's Camila Osorio.

The 29-year-old fifth seed looked out of sorts throughout her 7-5, 7-6 (7/4) win, at one stage in the opening set complaining of breathing difficulties before taking an extended medical timeout.

Jabeur has played only one tournament since being upset in last month's Wimbledon final by unseeded Czech Marketa Vondrousova.

Vondrousova, seeded ninth in New York, cruised into the second round on Tuesday with a 6-3, 6-0 win over South Korean qualifier Han Na-Lae.

Third seed Jessica Pegula meanwhile kept American hopes alive with a clinical 6-2, 6-2 defeat of Italy's Camila Giorgi.

Later Tuesday, second seed Aryna Sabalenka of Belarus opens against Belgium's Maryna Zanevska.

Sabalenka, who opened 2023 by winning her first Grand Slam title at the Australian Open, has a good recent record at the US Open, reaching the semifinals in 2021 and 2022.

The 25-year-old from Minsk says she has become mentally tougher after her previous defeats in the tournament.

"Winning tough matches, losing tough matches," Sabalenka said. "What I learned in the past, all these matches, you're not losing them, you're learning to become stronger.

"I know that in the future these tough losses will help me to win some great matches."