The afternoon matches saw scoreboards go dark due to a long power outage that affected 200,000 customers in the area. But play went on despite the lack of electricity, which shut down the umpires' microphones, and left the players without light or hot water in their clubhouse.
''It was cool to see the support she has here and it's fun to see that much support for tennis,'' Rogers said. ''I knew what I was getting into so I was prepared for it. I hope that doesn't happen too often, but I know she's a mega superstar up here.''
The 20-year-old Bouchard, who had not played since reaching the Wimbledon final last month, struggled in the first set, hitting normally routine shots long or wide.
Bouchard rebounded in the second, hitting the crisp mix of shots that took her to at least the semifinals of the first three Grand Slam events this year. But nothing worked for her again in the third set.
''I was feeling the pressure on the court and I was feeling kind of match rusty,'' Bouchard said. ''I knew it would be kind of a difficult situation, but I'm happy I was able to turn things around and not let it get away completely.''
The win put Rogers, a qualifier ranked 113th in the world, into the third round of the hard-court event. It also left the American 2-0 against Bouchard, whom she beat in a lower-level tournament in 2011.
Williams, who has played the Rogers Cup in Toronto before but never in Montreal, was on court in the early afternoon when the power went off.
''It was like going back to the Southern California juniors,'' she said. ''But I tried to think of it as positive, like 'this will be just like practice, so go ahead and relax. It will be a practice match.' You try to play those mind games when you're out there.''
It was an even first-round match, with Pavlyuchenkova ranked 24th and Williams 26th.
''We're both very good players and she's a dangerous player for the top players as well because she can do everything well when she's on,'' Williams said. ''It felt good to win the match and hopefully gain some momentum for the rest of the week.''
Williams is on the same side of the draw as her sister, top-seeded Serena Williams, who begins play Wednesday. They could not meet before the semifinals.
Serena Williams is to face Samantha Stosur, who beat qualifier Monica Puig 6-2, 6-2.
''I would love if we both got to the semifinals,'' Venus said. ''I fell a little short last week (at Stanford), but that's why I'm playing these matches this summer. I'm getting better rhythm as I go.''
Caroline Wozniacki, seeded 11th, had no trouble ousting Daniela Hantuchova 6-1, 6-1.
It was more trouble getting ready for the match in the dark.
''It's just so different: Everywhere, in the locker room, it's so dark,'' she said. ''We have to use our flashlights and phones. The water is freezing, as well.''
Petkovic, the 16th seed, was unable to play because she was sick.
''I pushed it back until the end and really tried to get healthy,'' she said in a statement. ''But I had a temperature and a fever and it's too risky to play like that in these kinds of conditions.
''I'm very disappointed.''
She plans to rest in bed for two or three days and try to be ready for a tournament next week in Cincinnati.
In other matches, No. 3 seed Agnieszka Radwanska beat Barbora Zahlavova Strycova 6-4, 6-4, and 14th-seeded Carla Suarez Navarro defeated Bojana Jovanovski 6-4, 6-3. Casey Dellacqua defeated Kirsten Flipkens 6-0, 4-6, 6-2.
Veteran Svetlana Kuznetsova retired from her match with Madison Keys due to an injury.