Third seed Mona Barthel was dumped out in the first round of the Coupe Banque Nationale after being beaten 6-7 (6), 6-4, 4-6 by Jelena Ostapenko on Monday.
Barthel, who arrived in Canada after a career-best third round appearance at the US Open, was playing Ostapenko for the first time in her career.
Ostapenko raced out to a 3-1 lead in the first set after breaking Barthel in the third game. However, Barthel broke back to bring herself level at 3-3 as the set progressed to a tiebreak, which Ostapenko won 8-6.
However, Barthel refused to go down without a fight and broke the 18-year-old Latvian early in a second set which she took 6-4.
It was Ostapenko who grabbed the decisive break in the deciding set though as she sealed victory in two hours and 15 minutes.
Fifth seed Annika Beck had no such problems as she cruised past Sharon Fichman 6-0, 6-1.
Tamira Paszek, Andrea Hlavackova, Sesil Karatantcheva, Naomi Broady and Louisa Chirico also won their respective first round matches.