New Zealand's Erakovic needed a second-set tiebreaker to get past American Mallory Burdette 7-6 (7-4), 6-3 at the Laval University campus.
France's Garcia, meanwhile, breezed to a 6-3, 6-4 decision over Canadian wild card Aleksandra Wozniak.
She now goes on to face American Christina McHale, who advanced with 6-2, 6-1 trouncing of 2010 champion Tamira Paszek of Austria.
Also notching a Day 1 win was Alja Tomljanovic of Croatia, who got past Spain's Maria Sanchez 6-2, 2-6, 6-3.
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