Naomi Broady made a winning start at the Coupe Banque Nationale in Quebec City with victory over Australian teenager Destanee Aiava.
The British number three, a 33/1 shot with Sky Bet, did not have things all her own way against her 17-year-old opponent.
But, after dropping the second set, Broady responded well in the third, serving 13 aces in total and dropping serve only once in a 6-4 3-6 6-3 victory.
Broady, who lost in the final round of qualifying at the US Open, next meets third seed Timea Babos in the next round.
Meanwhile on Monday number three seed Elise Mertens booked her place in the second round of the Japan Open with a straight-sets win over Evgeniya Rodina.
The Belgian - who is 41st in the WTA rankings - came through 7-6 (8/6) 6-1 in just over an hour-and-a-half against Russian Rodina.
Fourth seed Kristyna Pliskova of the Czech Republic also progressed after her 7-5 7-5 win over Chang Kai-chen of Chinese Taipei, while Alison Riske, the seventh seed, came from behind to defeat fellow American Madison Brengle 5-7 6-3 6-4.
Elsewhere, there were also first-round wins for Chinese pair Qiang Wang and Xinyun Han, while Slovakian Jana Cepelova advanced to the second round after Aliaksandra Sasnovich of Belarus retired, having lost the opening set 6-3 and being 1-0 down at the start of the second.