Top seed Karolina Pliskova and defending champion Simona Halep secured quarter-final berths at the WTA Rogers Cup, but Angelique Kerber was bundled out.
Naomi Osaka succumbed to an abdominal issue as world number one Pliskova won through to the last eight in Toronto on Thursday.
Simona Halep kept her title defence alive with victory over Barbora Strycova and she was joined by Wimbledon champion Garbine Muguruza.
However, third-seeded German Kerber went down to Sloane Stephens in the last 16.
PLISKOVA INTO MAIDEN QUARTER-FINAL
For the first time in her career, Pliskova is set to feature in the Rogers Cup quarters.
Pliskova benefited from an ailing Osaka, who was forced to retire in the third set as she trailed the top seed 6-2 6-7 (4-7) 1-0.
In the match, Pliskova fired down 12 aces and broke four times, while saving all three break points she faced.
Next up for Pliskova is sixth seed Caroline Wozniacki, who defeated Agnieszka Radwanska 6-3 6-1.
HALEP CRUISES THROUGH
The Romanian star dropped just one game in her routine 6-1 6-0 victory.
Halep was in complete control from the outset as she sealed the win in just 58 minutes.
Caroline Garcia awaits in the last eight after the Frenchwoman upstaged in-form Cici Bellis 6-4 6-2.
KERBER UPSTAGED BY STEPHENS
The former world number one was no match for Stephens, who eased to a 6-2 6-2 triumph in the third round.
Kerber only won four games as she crashed out of the tournament after less than an hour on court.
Stephens had never progressed beyond the third round of the Rogers Cup before Thursday's victory.
Standing in the way of the American and the semi-finals is Lucie Safarova, who eliminated Citi Open champion Ekaterina Makarova 6-3 6-7 (3-7) 6-2.
MUGURUZA SURVIVES SCARE
She was pushed to the limit but eventually prevailed 6-0 3-6 6-2 against Barty.
After racing through the opening set, Muguruza was pegged back by the Australian as the match headed to a decider.
But Muguruza was not to be denied a spot in the quarter-finals of the Rogers Cup for the first time in her career.
Muguruza will next face fifth seed Elina Svitolina, who ousted Venus Williams 6-2 6-1.