Aliaksandra Sasnovich fired Japan's Naomi Osaka a warning shot with a stunning straight-sets win over U.S. Open finalist and world No. 6 Karolina Pliskova on Thursday to advance to the quarterfinals of the Pan Pacific Open in Tokyo.

The Belarusian qualifier, ranked 107th in the world, meets Osaka in the last eight on Friday after pulling off a 6-4, 6-2 victory over her Czech opponent in 73 minutes at Ariake Colosseum.

"I was very focused. I was ready to go to Wuhan for the next tournament because I know Karolina is a really good player and I didn't think I would win today," said the 22-year-old Sasnovich, referring to the Wuhan Open set to get under way Sunday in the Chinese city.