Halep, seeded fifth, will have a chance to avenge her quarter-final Wimbledon defeat at the hands of Australian Open champion Kerber, who reached the final four in Montreal with an emphatic 6-2, 6-2 victory over teenager Daria Kasatinka.

"It was very tough, I feel really tired now, she played very well and she's very strong so I knew it was going to be like this," Halep said. 

"All I can say is that I'm very happy I could win against her, because we always have tough matches."

Once Halep shook off some early nerves, she was able to pressure the Russian veteran's serve and was rewarded when Kuznetsova surrendered an early break in the second set with a double fault.

Halep seized control for good with an early break in the third to keep alive her hopes improving on her runner-up finish in Canada last year -- when she retired from the final against Belinda Bencic with an illness.

While Kerber encountered little resistance against Russia's Kasatinka she said Halep wold be another matter.

"It's going to be tough," Kerber said. "We've played a lot of good matches in the past."

In the day's other quarter-finals, American Madison Keys took on Anastasia Pavlyuchenkova and Britain's Johanna Konta faced Kristina Kucova, the Slovakian qualifier who ousted Canadian Eugenie Bouchard in the third round.