Former champion Daniil Medvedev and third seed Jessica Pegula are safely through to the second round of the US Open after convincing opening victories in New York.
Medvedev, who won the title at Flushing Meadows in 2021, beat French qualifier Hugo Gaston 6-4 6-2 6-4 on Arthur Ashe Stadium.
The seventh seed was rarely troubled, hitting 10 aces and allowing Gaston just one break-point opportunity during the match.
Pegula also made an impressive start to her home Grand Slam, defeating Romania's Elena-Gabriela Ruse 6-3 6-2.
The American, runner-up at the US Open in 2024, needed one hour and 23 minutes to secure her place in the second round.
Elsewhere, two-time Grand Slam champion Barbora Krejcikova became the first seeded player to be knocked out, losing 7-6 6-2 to Uzbekistan's Kamilla Rakhimova despite saving six match points.
Ukraine's ninth seed Elina Svitolina raced past Argentina's Solana Sierra 6-1 6-2 in just 51 minutes, while fellow Ukrainian Marta Kostyuk and Italy's Jasmine Paolini also progressed.
Two former US Open finalists were forced out before playing their opening matches. Casper Ruud withdrew with a back injury, while 2014 champion Marin Cilic also pulled out because of injury.
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