It was another interesting turn of events in the Rogers Cup at Toronto as former world number one and Angelique Kerber failed to reach the next round after losing in straight sets to American Sloane Stephens.
The American, 24, beat Kerber 6-2 6-2 in 58 minutes to reach the last eight.
This adds to the American best of tennis displayed in Toronto as she saw off Petra Kvitova in the second round.
The win means Sloane Stephens will face Czech Republican Lucie Safarova in the quarter finals.
In other games, Wimbledon Champion, Garbine Muguruza reached the last eight at Toronto easing past Ashleigh Barty of Australia in a 2-1 set win.
The Spanish beat Barty 6-0 3-6 6-2 to advance to the next round and will face Ukrainian Elina Svitolina .
Karolina Pliskova, World number one, survived a scare to reach the next round after Naomi Osaka from Japan retired.
Naomi Osaka, 19, who was leading in the second tie-break could not continue the game leaving Pliskova to advance to the next round.
The Japanese was leading 6-2 6-7 (4-7) 1-0 but was forced to retire following an abdominal pain suffered.
Karolina Pliskova said after she made it to the last eight; “She played well, especially in the second set she was fighting pretty hard”.
“I was just trying to stay in the game and I didn’t know she was injured”.
Elsewhere it was a straight set win for Caroline Wozniacki, a former world number one who eased past Pole Agnieszka Radwanska 6-3 6-1 in only 78 minutes.
The win for Wozniacki means she will face current world number one Karolina Pliskova in the next round.
Simona Halep from Romania swept aside Barbora Strycova in straight sets of 6-1 6-0 to advance to the next stage while Czech Republican Lucie Safarova saw off Russian Ekaterina Makarova 6-3 6-7 6-2.
French Caroline Garcia is also into the next round with victory over 18-year old American Catherine Bellis.
Garcia beat the American in straight sets of 6-4 6-2 to qualify.
Lastly, Ukrainian Elina Svitolina was in the ascendancy as she beat American Venus Williams 6-2 6-1 to set up a clash with Garbine Muguruza.