Aleksandra Wozniak suffered a shoulder injury while warming up for her match against Melanie Oudin and was forced to retire on Thursday at the Bell Challenge tennis event.
The fourth-seeded Canadian was getting set to face off against Oudin, but suffered the injury in her warm-up session and could not play the match, allowing the American to advance to the quarterfinals.
In other action on Thursday, Georgia's Anna Tatishvili upended seventh-seeded Croat Petra Martic 6-2, 6-3, while eighth-seeded Czech Lucie Hradecka outlasted Canada's Eugenie Bouchard 7-6 (7-2), 2-6, 7-6 (7-4) on the indoor carpet at PEPS Laval University.
Belgian Kirsten Flipkens landed in the round of eight with a 6-7 (2-7), 6-2, 6-4 victory over Croat Mirjana Lucic. Flipkens ousted top seed Dominika Cibulkova on Wednesday night.
Flipkens will battle Tatishvili on Friday, while Hradecka will meet American Lauren Davis and Oudin will face off against France's Kristina Mladenovic in the quarterfinals.
The Czech Republic's Barbora Zahlavova Strycova defeated New Zealand's Marina Erakovic in last year's Quebec City finale.
The winner of this $220,000 tournament will collect $37,000.