Caroline Wozniacki said returning to elite level tennis after more than three years out felt like riding a bike after a break and there was no stopping the former world No 1 at the Canadian Open once she hit top gear on Tuesday.

The Dane, who said in June she was making a comeback after retiring in 2020 to start a family, barely looked like she had been away during her 6-2 6-2 victory over Kimberly Birrell in Montreal though there were some initial nerves.

"It's like riding a bike basically. You never forget it once you're in there, but at the same time it's different," Wozniacki told reporters.

"When you play the important points or see an opening, you get really excited, and then you may not hit it as clean and you're like 'ah, I have to start from scratch in the rally'."

Wozniacki, who has two children Olivia and James with her husband, former NBA player David Lee, said she was delighted to play in front of her family.

"I'm just excited to be back and competing and it's special having my family here," she said.

"Coming back as a 33-year-old that has played on tour for many years and doing it with my kids that now, especially the older one is starting to really understand and gets to really experience the world and different countries, it's so cool."

Wozniacki expects a tougher test against Wimbledon champion Marketa Vondrousova in the second round.

"Marketa has been on fire," Wozniacki said. "She played incredibly well at Wimbledon. Got out of some tough situations along the way but really kept her nerves cool in the finals.

"A tough opponent, a lefty. That's never easy to play a lefty with the ball going the other way. But, you know what, I have nothing to lose.

"I'm going to go out there and have fun regardless and see what happens."