Weather and withdrawals continued to plague the Rogers Cup on Friday.
Canada's Aleksandra Wozniak led American Christina McHale 7-6 (5), 5-2 when rain interrupted their third-round match.
Play was suspended for over six hours before the match was postponed until Saturday, when Wozniak will bid to become the first Canadian woman to reach the tournament's quarter-finals in 20 years.
Toronto's Patricia Hy-Boulais was the last to do it, losing to Monica Seles in the quarter-finals of the 1992 tournament in Montreal.
Earlier Friday, top-seeded Victoria Azarenka withdrew from the tournament because of a left knee injury.
Azarenka, who had a first-round bye, was tied at 3-3 in the first set when her second-round match against Austria's Tamira Paszek was suspended by Thursday night's rain.
"I hope it is a short-term thing but I don't know," Azarenka said. "I have to kind of stop and just take a little bit of time off because I absolutely had no rest for a long period of time, and just to settle it down and to go from there. But hopefully there is nothing serious."
The 23-year-old Belarusian, who is ranked No. 1 in the world, won two Olympic medals in London, taking gold in mixed doubles and bronze in singles.
"The last week took so much energy out of me that I absolutely had no time to recover and my body is feeling it," Azarenka said. "It was a little bit too much of a transition for me to come and start the training so I just felt my knee was not in good shape."
She said the knee did not bother her during the Olympic tournament, which was staged on the hallowed grass courts of Wimbledon.
"It actually just happened when I came here," Azarenka said. "When I started to train, the first time I hit it was a little bit of a compensation from the other court and it just happened."
Azarenka confirmed that she would not play the Western and Southern Open next week in Cincinnati. She said getting herself ready for the U.S. Open is her top priority.
"The first is to get healthy, to make sure that I'm a hundred per cent ready to play at the (U.S.) Open," Azarenka said.
Russia's Maria Sharapova, ranked No. 2 in the world rankings, withdrew earlier from the tournament due to a virus. The Olympic silver medallist and French Open champion was the third seed.
Tournament organizers hoped to be able to resume Wozniak's match Friday evening during an anticipated break from the rainfall that also disrupted Thursday's schedule.
Wozniak and McHale returned to the court nearly five hours after their match was interrupted. They finished their five-minute warmup and were ready to resume play when the rain began again.
Three other third-round matches were postponed until Saturday. Denmark's Caroline Wozniacki will play American Varvara Lepchenko, Li Na of China faces Italy's Sara Errani, and second-seed Agnieszka Radwanska of Poland plays South Africa's Chanelle Scheepers.
Fifth-seed Petra Kvitova of the Czech Republic made short work of France's Marion Bartoli in Friday's first match, dispatching the ninth seed 6-1, 6-1.
"Her performance today was extraordinary," Bartoli said. "When she plays like that she makes it very hard for her opponent to compete. I had break opportunities, and every time she served an ace."
Kvitova advanced to the quarter-finals where she will face the winner of the third-round match between Paszek and Carla Suarez Navarro of Spain.
Lucie Safarova, the No. 16 seed, upset fourth-seeded Aussie Samantha Stosur, 7-6 (9), 7-6 (5), to join her fellow Czech in the final eight.
Despite that result and the withdrawals of Azarenka and Sharapova, Kvitova refused to consider herself the favourite.
"A lot of great players are still playing so we'll see in the end," Kvitova said.
Safarova will face the winner of the third-round match between Italy's Roberta Vinci and sixth-seeded Angelique Kerber of Germany, who beat Russia's Ekaterina Makarova 6-3, 6-3.
Wozniacki, the 2010 champion, won her second-round match against qualifier Kiki Bertens from the Netherlands 7-5, 6-1.