NEW YORK, United States (AFP) — Using fist pumps and screams to focus her wandering thoughts and shake off stress, Japanese teen Naomi Osaka powered into the US Open third round yesterday, matching her best Grand Slam showing.

The 19-year-old Asian star, who ousted defending champion Angelique Kerber in her opener, outlasted 90th-ranked Czech Denisa Allertova 6-3, 4-6, 7-5 to reach the last 32 on the New York hard courts.

Osaka, who has a Haitian father and Japanese mother, hit 35 winners and made the last of 10 aces on match point after it withstood an appeal.

“[It was] just willpower, because I don’t really think I was playing that good,” Osaka said.

“I felt a little bit stressed because it was my first match after playing Kerber. So I felt a little bit of expectations to win and that’s why I wasn’t playing so well.”

Showing her emotions after key points and great shots kept 45th-ranked Osaka’s mind sharp over the one-hour, 52- minute affair.

“Saying ‘Come on’ is a way for me to stay concentrated because sometimes my mind wanders during the match,” she said. “And if I’m really pumped up, then I tend to focus really well.”

Osaka, the 2016 WTA Newcomer of the Year, can reach her first fourth round at a Grand Slam by beating 418th-ranked Estonian qualifier Kaia Kanepi tomorrow.