Sofia Kenin continued her fine run with a 6-2 6-2 win over Dayana Yastremska in Toronto.
American Kenin, who saw off number one seed Ash Barty in the second round, faced off against the Ukrainian who overcame former world number one Victoria Azarenka.
The world number 29 wrapped up the first set within 25 minutes and the second in 33, converting all four of her break points to set up a quarter-final tie with Elina Svitolina.
Svitolina, the sixth seed, beat Belinda Bencic 6-2 6-4 with the world number seven converting her fifth break point to seal her berth in the next round.
Defending champion Simona Halep breezed past Svetlana Kuznetsova 6-2 6-1 in just over an hour, while Marie Bouzkova also wrapped up a straight sets win over Jelena Ostapenko 6-2 6-2 in 80 minutes.
Serena Williams, who was beaten by Halep in last month's Wimbledon final, defeated Ekaterina Alexandrova 7-5 6-4 to reach the last eight.
Also through to the quarter-finals are Karolina Pliskova who beat Anett Kontaveit 6-3 7-5, Canadian Bianca Vanessa Andreescu who toiled to a three-set victory over fifth seed Kiki Bertens 6-1 7-6 (7) 6-4 and Naomi Osaka who beat Iga Swiatek 7-6 (4) 6-4.
