Photo by Andrew Ong/USTA.
Former world number one Simona Halep made a winning return to Grand Slam tennis after injury with a straight-set win over Camila Giorgi at the US Open.
The Romanian, who missed this year's French Open and Wimbledon with a calf tear, beat the Italian 6-4 7-6 (7-3).
Giorgi, ranked 36th in the world and winner of the Canadian Open this month, was a challenging prospect for Halep in the first round at a major.
But the two-time Grand Slam winner made the most of Giorgi's errors to advance.
The Italian made 30 unforced errors, nearly twice as many as Halep, as the Romanian 12th seed booked a second-round meeting with Slovakia's Kristina Kucova.
Among the women's top seeds in action later on day one at Flushing Meadows are Naomi Osaka, Aryna Sabalenka and Elina Svitolina.
Meanwhile British number one Johanna Konta has pulled out of the US Open, just hours before she was set to play her opening match on Monday.
Konta, 30, was due to face France's Kristina Mladenovic at about 22:00 BST.
The reason for Konta's late withdrawal was unclear.
Emma Raducanu's scheduled first-round opponent Jennifer Brady - the 13th seed and Australian Open runner-up - has withdrawn because of a knee injury.
The British teenager will instead play Swiss world number 128 Stefanie Vogele on her overseas Grand Slam debut.
Raducanu, 18, is aiming to back up her Wimbledon exploits - where she reached the last 16 as a wildcard - after coming through qualifying in New York.
After initially being set to play American Brady on Arthur Ashe Stadium, Raducanu now faces Vogele on court 17 at around 19:00 BST on Tuesday.