TOKYO — Katie Boulter has overcome a series of mediocre results on the WTA Tour’s Asian swing to advance to the Pan Pacific Open semifinals with a 6-2, 6-1 win over Bianca Andreescu on Friday.

The 28-year-old British player lost in recent weeks in the first round at Wuhan and in the second round to Coco Gauff at the China Open. But she dominated Andreescu, the 2019 U.S. Open champion who beat Serena Williams in straight sets in that final, on Friday in the first of four quarterfinals in Tokyo.

Boulter will play another Grand Slam singles champion, 2020 Australian Open winner Sofia Kenin, in the semifinals on Saturday. Kenin beat fifth-seeded Daria Kasatkina 6-3, 6-4.

Later, No. 1 seed and Paris Olympic gold medalist Zheng Qinwen beat eighth-seeded Leylah Fernandez 6-0, 1-6, 6-3. In the semifinals, Zheng will play Diana Shnaider, who advanced in a walkover when Sayaka Ishii was not able to take the court due to an undisclosed illness or injury.

In 2022, a 19-year-old Zheng reached the first WTA final of her career in Tokyo, beaten by Liudmila Samsonova in the title match. Two years later, she’s the reigning Olympic champion and was coming off a run to the Wuhan final two weeks ago that sealed her qualification for the WTA Finals in Riyadh next month.