(Reuters) - Fifth-seeded Romanian Simona Halep overcame a crisis of confidence in the second set to reach the final of the Rogers Cup with a 6-0 3-6 6-2 upset victory over second seed Angelique Kerber of Germany in Montreal on Saturday.

Halep had been a set and a break up before Kerber reeled off six straight games to lead 2-0 in the third before the Romanian regained control, sealing the win after a topsy-turvy encounter that lasted one hour 38 minutes in Montreal.

The 24-year-old, who was beaten by Kerber in the last eight at Wimbledon on July 5, will take on 10th-seeded American Madison Keys in Sunday's final at the hardcourt event.

Keys swept past unseeded qualifier Kristina Kucova of Slovakia 6-2 6-1 in Saturday's other semi-final, serving up nine aces as she wrapped up victory in just 51 minutes.

"I knew that it was going to be a tough one, always when I play against her it was a tough match," Halep told ESPN in a courtside interview after improving her career record against Kerber to 4-2.

"Mentally I am pretty strong and I am a little bit disappointed in the second set I gave up at 3-2. But this is me.

"I have to improve more in this way and I am just trying to enjoy more and more and to give everything I have to win."

A frustrated Halep smashed her racket on the ground during the seventh game of the second set after squandering her 3-2 lead and her coach, Darren Cahill, gave her quiet words of advice during the changeover.

"Take a deep breath ... control your emotions, keep a cool head and make good decisions," Cahill said.

Though Halep was also broken in the next game before Kerber leveled the match at a set all and then raced 2-0 up in the third, the Romanian heeded Cahill's advice and wrested back the initiative with a more positive approach from the baseline.

Halep won the last six games of the match, wrapping up victory on her fourth match point when a net cord by the left-handed Kerber bounced just wide.

"I just tried to be more aggressive, to hit the ball because I started to push it (in the second set) and she could take the initiative of the game and she could dominate," said Halep, who had lost her two previous matches against Kerber.

"And then I just wanted to finish the points and to go over her ... I am happy that I could finish it."

(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Andrew Both)