BASTAD, Sweden - Caroline Wozniacki made it through a rainy day at the Ericsson Open, defeating rising Belgian star Elise Mertens, 7-5, 4-6, 6-2. Katerina Siniakova stands between the top seed and her first title of 2017; the Czech youngster upset Caroline Garcia, 6-2, 7-5.

"It was a difficult match," Wozniacki said after the win. "She played very well, aggressively in the wind and the sun was very low. It was a combination of those three factors that made it so tough, but I tried to hang in there and be aggressive. I served well when I needed to."

Wozniacki endured a late start after multiple weather interruptions and was made to battle past an in-form Mertens, who reached a clay court final earlier this year at the TEB BNP Paribas Istanbul Cup, to earn her place in the final after two hours and seven minutes on court.

Recovering from a break down to start the match, Wozniacki took the opening set but came out on the wrong end of an early exchange of breaks to start the second. Facing a deciding set, she raced out to a 4-1 lead and never looked back, breaking at love to secure victory.

The Dane made three finals on hardcourts earlier in the season - Doha, Dubai, and Miami - before finishing runner-up to Karolina Pliskova for the second time in 2017 on the lawns of the Aegon International in Eastbourne. Her win over Mertens puts her into her first clay court final since 2015 at the Porsche Tennis Grand Prix in Stuttgart, and her first on outdoor clay since 2011, when the two-time US Open finalist was WTA World No.1.

"It's a positive that I put myself in the sitation where I'm in a fifth final. I'm definitely going to try and make this one.

"I haven't even thought about rankings; I'm just trying to play as well as I can."

Up next for Wozniacki is Siniakova, who dealt with more direct rain delays before knocking out French Open quarterfinalist Garcia in straight sets.

"Tomorrow, I'll have to play aggressively, because she's aggressive as well. I'll need to counter, get a lot of balls back, but also serve and return well."

Siniakova was serving for the match when rain fell once more, but nonetheless got the job done in emphatic style upon resumption.

"It's very tough, becuase you're still waiting, but need to stay focused to be able to go on the court again. I kept trying to focus on my game and I'm so happy I did it."

The 21-year-old Czech made her first WTA final in Bastad a year ago, and has since won her first title earlier this year in Shehzhen.

"It's amazing. The atmosphere is really good year, so I'm happy I could come back. I wasn't sure if I would play here again, but I'm back and in the final!"