British number one Katie Boulter sailed through her opening match to set up a second-round meeting with Coco Gauff at the WTA National Bank Open in Montreal.

World number 72 Boulter is yet to drop a set in Canada after previously easing through two qualification rounds.

Sixth seed Gauff had a first-round bye, but fellow American Venus Williams lost 6-2 7-5 to compatriot Madison Keys.

Williams, 43, saved seven match points to break serve at 5-4 down in the second set but Keys immediately broke back before finally converting a ninth match point overall to serve out for the win.

Boulter, meanwhile, never looked back after breaking world number 103 Marino's serve to love in the fifth game of the opening set and sealed it with another break on her first set point.

She faced four break points on her own serve in the second set but saved them all, including two in a key game at 3-1 up, before completing a relatively comfortable victory.

Karolina Pliskova will face Poland's world number one Iga Swiatek in round two after the Czech took two hours and 22 minutes to beat China's Zhu Lin 6-3 6-7 (8-10) 6-2.

Belarus' Victoria Azarenka beat Poland's Magda Linette 6-3 6-0 for her 187th career win at WTA 1000 level, breaking the record set by Simona Halep since the level began in 2009.

Former world number one Caroline Wozniacki, 33, makes her much-anticipated return to the court on Tuesday evening, facing Australian Kimberly Birrell in the Dane's first competitive match since the 2020 Australian Open.