Daniil Medvedev had an easy start to his U.S. Open title defense, beating Stefan Kozlov 6-2, 6-4, 6-0 on Monday.

On the same Arthur Ashe Stadium court where that night Serena Williams was set to begin what could be the final tournament of her career, the top-seeded Medvedev looked just as strong as he did in sweeping past Novak Djokovic in last year’s final for his first major title.

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Medvedev advanced to face Arthur Rinderknech of France. The Russian is trying to become the first repeat champion at the U.S. Open since Roger Federer won five straight from 2004-08.

“I need to be at my best on Wednesday and I’m going to try to make it,” Medvedev said.

Andy Murray was another early winner, 10 years after winning the first of his three Grand Slam titles in Flushing Meadows. He had one of the first upsets of the tournament by beating No. 24 seed Francisco Cerundolo of Argentina 7-5, 6-3, 6-3.

“It seems like a long time ago,” Murray said of his victory over Novak Djokovic in 2012. “A lot’s happened since then in my career.”

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Djokovic couldn’t travel to the tournament this year because he isn’t vaccinated against COVID-19.

Many fans arriving for the day session at the final Grand Slam event of the season were focused on the match that would lead off the action at night. Williams, the 23-time major champion who has said she is preparing to end her tennis career, was scheduled to face Danka Kovinic.

Williams figured to face more comfortable conditions after a hot start under sunny skies in Flushing Meadows. Leading 3-0 in the third set, Medvedev told the chair umpire he wanted a bag of ice so he could put it on his head.

“Pretty hot and humid here,” Medvedev said after the match.

No. 29 seed Tommy Paul overcame the heat to outlast Bernabe Zapata Miralles 4-6, 6-3, 2-6, 6-0, 7-5 in 3 hours, 10 minutes. Fellow American Sebastian Korda also got his first win at his home Slam, beating Facundo Bagnis in four sets.

Another American advanced in an upset, with J.J. Wolf ousting No. 16 seed Roberto Bautista Agut in straight sets.

Third-seeded Maria Sakkari and No. 17 Caroline Garcia were among the early winners on the women’s side, with Sakkari overcoming Wimbledon semifinalist Tatjana Maria in three sets.