Three-time winner Serena Williams moved into the National Bank Open second round with a 6-3, 6-4 win over Spain's Nuria ParrizasDiaz on Monday.

During a nearly two-hour match played in hot and humid conditions, Serena Williams was forced to dig deep during her only other singles match since returning to action at Wimbledon in June.

I feel like I'm on the right track. Williams told reporters that he wasn't where he wanted to be

It's similar to getting that to the court in practice. I'm the kind of person who just needs one or two things to click. I'm waiting on that to happen.

Williams, one of 14 major winners in the main draw of an event that is a tune-up for the US Open, won the opener on her fourth set point.

Williams did well to hold serve in a physically demanding 18-minute game during which she used her power to fight off four break points to get to 4-4 in the second set.

Williams broke her opponent after she missed a backhand and went on to win the match.

It takes a lot to get one win. Williams said that he was happy to have a victory. It has been a while. I didn't remember what it was like.

The 12th seed or the Czech Tereza Martincova will be Williams' next opponent.

After retiring from her second-round match in Washington due to illness, Halep needed just 61 minutes to defeat Croatia's Donna Vekic.

The first set was easy for Halep as she breezed through it in 21 minutes.

"It's not about the result, it's more about the way I played," Halep said during her on court interview. I've been very aggressive and I want to play fast every day.

When the event was held in Montreal in 2016 and 2018, Halep won her two Canadian titles.

The clash with either American 10th seed Coco Gauff or Madison Brengle will be the next one for the Kazakh.

Canadian 13th seed Leylah Fernandez will play Australian Storm Sanders in Toronto before Venus Williams plays Jil Teichemann in Switzerland.