Montreal - Top-seeded Lucie Safarova of Czech Republic booked her quarter-final berth at the WTA tournament in Quebec City on Thursday with a 6-4, 6-3 victory over Sofia Kenin.
Safarova fired 10 aces as she powered past the 18-year-old American, who is ranked 112th in the world.
In the quarter-finals, Safarova will face 32-year-old fellow Czech Lucie Hradecka, who ousted 17-year-old Canadian Bianca Andreescu 2-6, 6-2, 7-5.
Andreescu served for the match at 5-3 in the final set, but Hradecka won the final four games to seize the victory.
Seventh-seeded Alison Van Uytvanck of Belgium also reached the quarter-finals, fending off a late challenge to beat New Zealand's Marina Erakovic 6-4, 7-6 (7/4).
"I was up two breaks in the second set, and she fought really hard to come back and played good tennis," Van Uytvanck said. "So I'm happy with the win and the way I'm playing."
Van Uytvanck led the second set 3-0 before Erakovic battled back. The Kiwi held a set-point at 5-4 but couldn't convert and Van Uytvanck prevailed in the tiebreaker.
Van Uytvanck next faces US qualifier Caroline Dolehide, who had advanced on Wednesday when defending champion and second seed Oceane Dodin withdrew because of dizziness.
Eighth-seeded Viktorija Golubic of Switzerland was denied a quarter-final spot by American Sachia Vickery, who rallied for a 2-6, 6-3, 6-4 victory.
Vickery will face fourth-seeded Tatjana Maria of Germany for a semi-final berth. The remaining quarter-final pits third-seeded Hungarian Timea Babos against Canadian Francoise Abanda.
Results from the WTA tournament at Quebec City, Canada on Thursday (x denotes seeding):
Lucie Safarova (CZE) bt Sofia Kenin (USA) 6-4, 6-3
Lucie Hradeck (CZE) bt Bianca Andreescu (CAN) 2-6, 6-2, 7-5
Sachia Vickery (USA) bt Viktorija Golubic (SUI x8) 2-6, 6-3, 6-4
Alison Van Uytvanck (BEL x7) bt Marina Erakovic (NZL) 6-4, 7-6 (7/4)