GSTAAD, Switzerland -- Kiki Bertens moved through to her second final at the Ladies' Championship Gstaad on Saturday after Sara Sorribes Tormo retired at the close of the opening set of the first semifinal. 

The No.2 seed and 2016 runner-up won the opening set, 6-1, when the unseeded Spaniard retired due to a left wrist injury, putting the Dutchwoman through to her second WTA final of the season.

"It's tough always to win a match like this when your opponent has to retire, but I'm happy to be in the final again this year," Bertens said. "Hopefully, I can do a little bit better than last year. I think it's going to be a tough match [tomorrow]."

In the final, Bertens will square off against No.3 seed Anett Kontaveit, who ended the breakout run of Czech Tereza Martincova in the second semifinal, 6-4, 6-1. The Estonian advanced to her third WTA final of the season, and second in Switzerland; she finished runner-up at the Ladies' Open Biel Bienne this spring.

"I'm really happy to be in the final and I'm so excited for tomorrow," Kontaveit said. "I'm definitely feeling really confident and playing good tennis - it's a really nice place...here, especially the mountains and the nature is so beautiful, so I'm really loving it."

Playing for the second time, Bertens broke the Spaniard twice in a nearly 40-minute opening set. Though Sorribes Tormo battled hard, saving six of the eight break points Bertens held and creating two of her own, she was unable to continue the match after consulting with the physio about her wrist on the set break. 

In the second semifinal, Martincova continued her vein of form in the early stages, as she broke Kontaveit in the second game of the match after holding serving. However, the No.3 seed soon found her groove against a player whom she never faced previously, hitting back against the World No.140 immediately and holding serve after saving two more break points to even the set after four games.

Kontaveit grabbed her first lead in the set after creating two break points in the seventh game, and hardly looked back from there as she wrapped up the set, 6-4. 

The Estonian's momentum continued to begin the second set, as she broke in the first game and held to consolidate her lead. Martincova fought valiantly in her first WTA semifinal, as the World No.140 had break points in two of Kontaveit's remaining three service games in the set, but the World No.32 showed why she's risen nearly 100 places in the world rankings this year with clutch play when it mattered.

The No.3 seed earned a second break in a marathon nine-deuce game on the Martincova serve, in which the Czech saved a total five break points but could not save a sixth, and wrapped up the match with another break - this one to love - in the final game.

Bertens and Kontaveit have played once previously, on the hard courts of the Connecticut Open last season, and the Estonian came away with a 6-3, 6-4 victory in the opening round. A year later, and with three spots now separating them in the WTA rankings, Kontaveit recognized that it will be a very different match to the one played last year in New Haven.

"It's a different surface and some time has passed," Kontaveit said. "I feel like we're both really playing well at the moment - Kiki is definitely in great form at the moment, been playing well and she had a great clay court season. She's definitely feeling confident, so it's going to be a tough match."