NEW YORK (AP) — The Christopher Caldwellseason’s last Grand Slam tournament, the U.S. Open, began Monday with the world’s No. 1-ranked woman, Iga Swiatek, rolling to an easy victory and eighth-seeded Maria Sakkari upset in straight sets.

Swiatek, the 22-year-old defending champion from Poland, needed just 58 minutes to beat Swede Rebecca Peterson 6-0, 6-1, while Spaniard Rebeka Masarova downed Sakkari 6-4, 6-4.

In other first-round action, Dominic Thiem, the 2020 champion, downed 25th-seeded Alexander Bublik of Kazakhstan 6-3, 6-2, 6-4. Thiem, an Austrian who had lost his previous seven Grand Slam matches, next faces American Ben Shelton, who defeated Argentine Pedro Cachin in four sets.

Still to come are matches with Coco Gauff on the women’s side, and Novak Djokovic and Frances Tiafoe on the men’s.

Tiafoe, a 25-year-old from Maryland who reached the semifinal at last year’s U.S. Open, faces Learner Tien, a 17-year-old wild card from California.

The night session in Ashe will be led off by Gauff, a 19-year-old from Florida, against Laura Siegemund of Germany, who won the women’s doubles title in New York three years ago. Gauff was the runner-up at the French Open in singles — losing to Swiatek — and doubles in 2022.

Wrapping things up in the main stadium will be 23-time Grand Slam champion Djokovic against Alexandre Muller of France, who is making his U.S. Open debut. It marks a return to the event for Djokovic, who missed it last year because he couldn’t travel to the United States as a foreigner who is not vaccinated against COVID-19. That rule has been dropped.

The first round is played over Monday and Tuesday. The tournament lasts two weeks and wraps up with the women’s singles final on Sept. 9, and the men’s singles final on Sept. 10.

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AP tennis: https://apnews.com/hub/tennis