Osaka reaches US Open third round after nervy match

Two-time champion Naomi Osaka has advanced to the US Open third round after a flurry of mistakes, fighting past Czech Katerina Siniakova 6-2, 5-7, 6-1 on Thursday.

The 2018 and 2020 champion was too good to claim the first set, with just four unforced errors, breaking her opponent to love in the fourth game. The Czech committed three double faults in the eighth game before letting Osaka break again on set point with an unforced error.

Siniakova made a comeback in the second set, where Osaka struggled for form just as the Czech hit her stride, and the Japanese put up 20 unforced errors that gave her opponent too many chances.

After trading breaks twice in the second set, Osaka looked frustrated and tapped her racket on the court after hitting the net with a backhand and handing Siniakova the break with another backhand error in the penultimate game.

Osaka went to the locker room before the third set, a decision that changed the momentum of the game.

"I just told myself that it's an honour to play on this court," said Osaka, who reached the semi-finals a year ago. "I just want to keep playing in front of you guys, if possible."

She came back on the court with new resolve, winning the first three games and saving two break points in the fifth before closing it out with an unreturnable serve.

"The match was definitely really tough. I don't know, I just felt like I had to fight," said Osaka, who will next play Belgian Elise Mertens.

"I think I was a little bit too hard on myself, so I took the bathroom break, tried to regroup and have no regrets."