Australian Daria Gavrilova is into the second round of the Rogers Cup after beating Spain's Lara Arruabarrena in straight sets in Canada.
Gavrilova, ranked 25 in the world, beat Arruabarrena 6-3 6-3 in the first round of the WTA event in Toronto on Monday.
The 23-year-old Gavrilova didn't face a break point in closing out the match in 71 minutes.
She broke world No.64 Arruabarrena to love in the fourth game of the match to take the first set, before taking the two break points on offer in the second.
Gavrilova will face Barbora Strycova in the second round after the Czech's 6-2 6-3 win over Kristina Mladenovic of France.
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Venus Williams prevailed in a three-setter but French Open champion Jelena Ostapenko and 13th seed Mladenovic crashed out in the first round.
Williams outlasted a lengthy rain delay and pesky Romanian opponent Irina-Camelia Begu to win her opening match 6-1 3-6 6-3.
Less than a month after her run to the Wimbledon final, where she lost to Spain's Garbine Muguruza, 37-year-old Williams again had to turn back time against a young challenger.
After taking the opening set in dominant fashion, the American found herself in a fight as Begu rallied back to win a set before rain suspended action for more than an hour.
The decisive set was a rollercoaster with Williams moving ahead 3-1 only to lose consecutive games before bouncing back to seize three straight games and the match.
Earlier, Mladenovic was swept aside 6-2 6-3 by Czech Barbora Strycova while Ostapenko fell to American Varvara Lepchenko as upsets marked the start of the tournament.
The 12th seeded Ostapenko lost 1-6 7-6 (7-2) 7-6 (7-5) to Lepchenko in two hours and 36 minutes.
After breezing through the first set, the 20-year-old Ostapenko's nerves began to show and unforced errors helped Lepchenko, 31, take the final two sets in tiebreaks.
Fan favourite Petra Kvitova, determined to improve following a knife injury to her hand inflicted by an intruder at home, beat Spaniard Carla Suarez Navarro 6-1 7-6 (7-5).
The Czech's served six aces and recorded 32 winners.
