U.S. Open champion Naomi Osaka booked a spot in the China Open semifinals following a hard-fought, three-set victory over home favorite Zhang Shuai on Friday.

World No. 6 Osaka, who represents Japan, fought from a set down to beat China's world No. 45 Zhang 3-6, 6-4, 7-5 in a match lasting more than two and a half hours at Beijing's National Tennis Center.

The eighth-seeded Osaka started slow, committing 22 unforced errors in the first set against Zhang's eight.

They split the first eight games in the second set, but Osaka held off Zhang and claimed two games in a row. Osaka powered to victory by firing 51 winners throughout the match, while Zhang only had 13.

"(Zhang)'s such an incredible player and she's really sweet. It was really hard to play against her here," Osaka told a post-match interview.

Osaka, who won her maiden Grand Slam at Flushing Meadows in early September, will face Latvia's world No. 20 Anastasija Sevastova in the semifinals. Sevastova defeated Slovakia's Dominika Cibulkova 6-3, 7-6(5) in their quarterfinal.

"I'm just thinking one match at a time, and I know it can only get harder from here," Osaka said. "Especially by the way she (Zhang) played, I know everyone wants to play really well."