Defending champion Oceane Dodin battled through the opening round of the Coupe Banque Nationale as fellow seed Timea Babos also advanced.
Dodin, who claimed her maiden WTA Tour title in Quebec City last year, overcame local qualifier Gabriela Dabrowski 5-7 7-5 6-4 on Monday.
The Frenchwoman came from a set and 5-3 down, reeling off four consecutive games in the second before sealing her win at the WTA International event.
Awaiting Dodin in the second round is Caroline Dolehide after the American's 6-3 6-2 win over Charlotte Robillard-Millette in a battle between two teenage qualifiers.
Third seed Babos was also tested, needing more than two hours to get past Jamie Loeb 7-6 (7-4) 5-7 6-2.
Babos will next meet Naomi Broady, who edged past Australian teenager Destanee Aiava 6-4 3-6 6-3.
The only other seed in action was Varvara Lepchenko, the American proving too good for Aleksandra Wozniak 6-1 2-6 6-1.
A two-time runner-up at the event, Marina Erakovic came through her opener, cruising past Alla Kudryavtseva 6-4 6-1.
Grace Min also advanced, beating Jessica Pegula for the fourth consecutive time with a 4-6 6-4 6-0 victory.