No.46 Petra Martic advanced to the quarterfinals of the Toray Pan Pacific Open with a 6-3, 6-4 win over No.6 seed Karolina Pliskova.
Into her fourth quarterfinal of the season, Martic will face Zhang Shuai next.
In a match that saw Martic play the big points better, the Croatian snapped her two-match losing streak to Pliskova and move ahead 4-3 in their tour-level head-to-head.
"I'm really happy with today's match. Karolina is a great player, beat me quite a few times in the past," Martic said. "I expected a tough match and I'm just happy to win it."
Martic saved 9 of 10 break points in the match, including four in the fifth game of the second set. Beguiling the Czech with backhand slice and court coverage, Martic broke serve four times to make her first Tokyo quarterfinal after 1 hour and 35 minutes.
Pliskova finished the match with 23 winners to 25 unforced errors, while Martic hit 17 winners to 22 unforced errors. But it was the missed opportunities for the former champion that ultimately decided the match.
No.30 Liudmila Samsonova followed Martic into the quarterfinals later in the day, defeating Wang Xinyu 7-6(5), 6-3. Samsonova, who has now won 15 of her last 16 matches, will face No.3 seed Garbiñe Muguruza next.
With the roof closed due to the rain, Samsonova fired 13 aces and faced just two break points in the match.
"It's not easy to play indoor when you prepare the match outdoors," Samsonova said. "So it was a little bit different conditions. She was playing amazing, I think she's a great player already. My serve today was hopefully good enough to maintain my game."