CINCINNATI, OH, USA - Kiki Bertens' sizzling summer has shown no signs of cooling off.

The World No.17 rallied from a set down to defeat No.8 seed Petra Kvitova and reach the final of the Western & Southern Open on Saturday, 3-6, 6-4, 6-2.

For the second time in as many weeks, Bertens scored a victory over the two-time major champion on the North American hardcourts, having beaten Kvitova en route to the quarterfinals in Montreal.

"I'm feeling great. I'm really happy I won this match. It was a really tough one, but I'm so happy to be in the finals here," Bertens said on-court after the match.

"It feels great. We've put a lot of work in to get more fit, and play more aggressive on the hard courts, and it's working out."

Her seventh straight victory over a Top 10 player did not come easily, however, as she was forced to come from behind after losing the last five games of the first set.

"I think today in the beginning I was struggling a little bit, with the serve, especially. Petra was returning really well and also serving good," she said.

"In the second set I was getting better. Until the end I felt fit, was going for my shots. My serve was going well in the end. It was just a matter of keeping going, I guess. I think over the last year we practiced a lot, like, to play more aggressive. It's working out well now, so, yeah, I'm really glad with that."

After she hung on in a wild second set which saw seven breaks of serve, Bertens' serve rounded into form in just the right time in the decider.

The Dutch No.1 didn't face a break point in the final set and dropped just three points on serve overall, going a perfect 13-for-13 behind her first set. 

The World No.17 has recorded all seven of her Top 10 victories in her current streak over her last three events, having beaten a pair of players in the world's elite at Wimbledon and in Canada.

This week, she added Kvitova's named to Caroline Wozniacki and Elina Svitolina's in her list of scalps.

In another tidy performance, Bertens hammered 23 winners to 21 unforced errors over the course of the match, tallied 10 aces, and grew in confidence over one hour and 54 minutes.

The Czech No.1 accumulated 48 unforced errors over the course of the match, including eight double faults, and lost serve seven times as she started to feel the effects of her third marathon three-setter in the Cincinnati sun.

On Sunday, she will contest her third final of 2018 - which have all come at Premier level - and first away from clay against either World No.1 Simona Halep or fast-rising Belarusian Aryna Sabalenka.

"I think that's going to be a great match. Halep is playing some great tennis and she won of course last week. Yeah, she's having her shots there, but Sabalenka, also, she's having a great year, hitting the ball so hard," Bertens said.

"I'm looking forward to whoever it's gonna be. I'm really happy that I'm in this final. For me, it doesn't matter who's gonna win."