World No.1 Naomi Osaka survived a scare to start her US Open title defence with a hard-fought 6-4 6-7 (5-7) 6-2 first-round victory over Anna Blinkova.
Osaka, 21, fought from 3-0 down in the first set, but wasted a match point at 6-5 in the second, forcing her to go the full distance against the 84th-ranked Russian at Arthur Ashe Stadium.
- Federer overcomes Sumit Nagal, Djokovic breezes through first round
- Angelique Kerber crashes out in first round upset
Osaka was playing her first match at the site, since she became the first Japanese national to win a Grand Slam title in a controversy-marred final against Serena Williams last year.
She went on to lift the Australian Open trophy in January, but has not won a tournament since.
Afterwards, Osaka admitted the nerves that come with being a first-time defending champion played a part in her slow start.
"I don't think I've ever been this nervous in my life," she said in an oncourt interview.
"I don't think I ever really found my rhythm, but I just fought as hard as I can."
Osaka chose to look on the bright side of her unexpectedly competitive match.
"It helps me a lot, because I learn from the tougher matches. It helps me prepare to have to adjust my game plan throughout the match."
Next up for Osaka is a second-round meeting with Poland's Magda Linette.
Meanwhile, two-time Wimbledon champion Petra Kvitova eased past Czech compatriot Denisa Allertova with a 6-2 6-4 victory to move into the second round.
Kvitova, runner-up at the Australian Open this year, converted four break points and smashed 16 winners, while Allertova double-faulted six times and made 33 unforced errors to hand the sixth seed victory in 79 minutes.
Two-time Grand Slam winner Garbine Muguruza of Spain suffered her second straight first-round exit following Wimbledon, losing 2-6 6-1 6-3 against American Alison Riske in a match that lasted just over two hours.
Riske converted seven break points and smashed 39 winners to advance.
Seventh-seeded Kiki Bertens made quick work of Paula Badosa, beating the Spaniard 6-4 6-2 to advance to the second round.
Bertens hit 23 winners and won nine more points at the net, as she wrapped up the contest in just over an hour.
DPA