Instead, the former world No. 1 from Denmark will play Shelby Rogers, the American qualifier who put a quick end to Bouchard's homecoming tournament in the second round.
Wozniacki breezed through a second match in a row with a 6-1, 6-2 victory over Klara Koukalova on Wednesday. She has lost only five games in two matches in the hard-court event.
"It's my favorite surface," Wozniacki said. "I've been playing pretty well lately.
"Montreal has always been a good place for me, winning here a few years ago (2010). I'm feeling good and hopefully I can keep going."
Wozniacki is coming off her first win of the season at the Istanbul Cup, where she dropped only two games while beating Roberta Vinci in the final.
In the night feature, top-ranked Serena Williams dispatched Samantha Stosur 6-0, 6-2 in a match interrupted 28 minutes by a sprinkle of rain. Williams is coming off a victory Sunday in Stanford, Califiornia -- her fourth victory of the season.
Williams needed only 59 minutes of playing time to beat Stosur. The American set up a match against 15th-seeded Lucie Safarova, a 6-4, 6-2 2 winner over Magdalena Rybarikova. Williams is 6-0 against Safarova.
"She is an interesting player," Williams said. "She's extremely tricky. We've had some tough matches. I know we've gone to three sets on occasions. It's definitely not an easy match for me."
Williams has won the Rogers Cup three times when it is held on alternate years in Toronto, including last year, but she has not played in Montreal since she retired from the final with an injury in 2000.
"I'm really happy to be a part of the tournament this year. It's just really cool," she said. "I've actually been studying French for most of my life, so yeah, I should be able to speak even better, to be honest. I love it in Canada because I understand everything. It's a lot easier for me to speak. The accent is much easier for me to understand."
The 13th-ranked Wozniacki will face Rogers, who played the spoiler as Bouchard battled rust and her nerves Tuesday night.
"I know how she looks like, but I don't know much about her game," Wozniacki said. "I will definitely have my team tell me how she plays."
It promises to be a quieter match than if it was Bouchard, who had the packed center court solidly behind her, as well as her Genie Army fan group in from Australia.
"I don't really care, to be honest," Wozniacki said. "Obviously, Rogers must have played really well to beat Genie. With the whole crowd, as well, for Genie, you know it wasn't easy. But for me, it's a new match. It doesn't matter who's on the other side."
If she keeps winning, it may draw attention back to her tennis game and away from her famous split in May with golfer Rory McIlroy.
Both players seem to be doing better since then, with McIlroy following his British Open title with a win at last week's Bridgestone Invitational.
"I've moved on. I hope everyone else has moved on, too," said Wozniacki, who will run the New York Marathon in November, when the wedding was to have been.
"I was happy that I was able to turn it around," Sharapova said. "I didn't feel good. I made a lot of errors in the first set. When you're able to finish stronger than your start, that's always a positive because you give yourself an opportunity to keep playing in the tournament."
Her next opponent is 14th-seeded Carla Suarez Navarro, who got past lucky loser Karolina Pliskova 6-1, 3-6, 6-3.
The 22-year-old will face eighth-seeded Victoria Azarenka in the third round.
Watson won two qualifying matches on the weekend before downing Tereza Smitkova in the first round. Cibulkova was coming off a first-round win over 17-year-old Francoise Abanda of Montreal.