TOKYO — Japan's Naomi Osaka exuded a major champion's aura Friday as she dispatched Barbora Strycova 6-3, 6-4 to reach the Pan Pacific Open semifinals, despite being nowhere near her best.

The third seed, who stunned Serena Williams to capture the US Open title earlier this month, failed to hit the same heights she did on that historic night in New York.

But she still had too much firepower for Strycova in Tokyo, advancing to face Italy's Camila Giorgi in the last four.

Eighth seed Strycova had little answer to her opponent's venomous hitting and the world number seven bagged the first set with a sledgehammer forehand that almost tore the racquet from the Czech's hand.

The 20-year-old Osaka, contesting her first tournament since becoming Japan's first Grand Slam singles winner, never looked back against a player 12 years her senior, with another forehand rocket bringing up a first match point.

Strycova saved that one but moments later, Osaka fired a bruising serve into the body to extend her current winning streak to nine matches.

"It would mean a lot to win this tournament," said Osaka, who reached the Tokyo final in 2016. It definitely is on my mind," added Japan's latest sporting celebrity, who has a Japanese mother, a Haitian father and was raised in the United States.

"But tomorrow is going to be a hard match. I've never played (Giorgi) before but I know she's a very difficult player to play against."

Giorgi, who knocked out top seed and defending champion Caroline Wozniacki on Thursday, was leading former world No. 1 Victoria Azarenka 5-3 when the Belarusian retired with stomach pains.

"I'm looking forward to it," shrugged Osaka, backing herself to fix the gremlins that plagued her serve against Strycova.

"My serve will be there when I'm in danger. That's how I saved a lot of break points at the US Open and I'm not trying to do anything different."

Earlier, fourth seed Karolina Pliskova saved two match points before the former women's top-ranked player ended American qualifier Alison Riske's run with a 6-1, 6-7 (5-7), 7-6 (7-4) victory.

The Czech, who smashed a racket in disgust after squandering multiple chances at 5-5 in the deciding set, completed a "lucky win" with a sliced backhand that Riske wafted into the net after two hours, 40 minutes.

"It was an important win for me," said Pliskova after reaching her first Tokyo semifinal. "I'm just happy to be able to fight back — she was a little bit better than me, but you need a bit of luck in tennis."

Pliskova faces Croatia's Donna Vekic in the last four after she upset second seed Caroline Garcia 6-3, 6-4.

Garcia blew an early break to allow Vekic to take the opening set and the Frenchwoman suffered a carbon-copy letdown in the second, the Croatian ending her misery with a backhand winner. — AFP