Ranked 112th in the world, Marino signaled the exit door to her compatriot Victoria Mboko, 519th, in two identical sets of 6-3 after a battle that lasted only 64 minutes.
The 31-year-old outplayed her rival, a teenager who turns 16 on August 26, both on serve and in return.
Marino had seven aces and only one double fault, the opposite of Mboko, who posted a 2-7 ratio. She also smashed it four times, twice per march, and granted him only one opportunity to reciprocate, to no avail.
The Torontonian has an appointment in the second round with the Italian Jasmine Paolini, 3rd seed in Granby and 57th in the WTA rankings.
Earlier in the day, Canadians Marina Stakusic, 630th, and Cadence Brace, 646th, in turn clinched the tournament victory.
Stakusic prevailed 4-6, 6-3 and 6-2 against Australian Jaimee Fourlis, 152nd, while Brace upset Kaja Juvan, 7th seed in Estrie and 70th in the world, in two sets of 7-5 and 6-3.
The Granby tournament is now a WTA 250 category tournament, after having had Challenger status. Some headliners of the women’s circuit have therefore added the event to their calendar, before heading to New York, where the fourth round of the grand slam will be held in a week.
The Russian Daria Kasatkina, 10th, is the favorite of the competition, which she started with a win of 6-7 (4/7), 6-4 and 6-2 against the Belgian Greet Minnen.
Other first-round results:
- Nuria Parrizas (ESP/no 5) defeated Rebecca Peterson (SWE) 6-2, 6-1
- Anna Bondar (HUN/no 4) beat Kayla Cross (CAN) 6-3, 6-4
- Diane Parry (FRA) beats Lulu Sun (SUI) 6-4, 6-2
- Tereza Martincová (CZE/no 8) beat Oceane Dodin (FRA) 6-2, 7-5
- Marta Kostyuk (UKR/no 10) defeated Tamara Zidansek (SLO) 6-1, 7-5
- Jasmine Paolini (ITA/no 3) defeated Himeno Sakatsume (JPN) 7-6 (8/6), 6-4
- Wang Xiyu (CHN) beats Jamie Loeb (USA) 7-6 (7/4), 6-7 (5/7), 6-2