British number one Heather Watson progressed to the third round of the Rogers Cup in Montreal after a three-hour victory over 10th seed Dominika Cibulkova.
Two service breaks saw Watson to a one-sided first set but her Slovakian opponent hit back to force a decider.
Watson, 22, held her nerve in a third set that went to a tie-breaker before prevailing 6-2 6-7 (3-7) 7-6 (7-5).
The world number 57 meets Victoria Azarenka of Belarus in the next round.
She was impressive in compiling her first ever win over world number 12 Cibulkova, hitting 10 aces without reply and forcing six breaks of service.
Her next opponent, 25-year-old Azarenka, is a former world number one and two-time Grand Slam title winner.
Watson has never beaten Azarenka, winning just four games in total from three straight-sets defeats, the most recent of which came at Miami in March 2012.
Serena Williams, Petra Kvitova, Maria Sharapova and Angelique Kerber are also through to the third round in Montreal.