ST. PETERSBURG, Russia - The lone Russian remaining at the St. Petersburg Ladies' Trophy scored a statement win on Friday afternoon, as Daria Kasatkina knocked off World No.1 Caroline Wozniacki to reach the semifinals, 7-6(2), 6-3.

The No.8 seed scored her second career win over a reigning World No.1, having beaten Angelique Kerber when the German held the top spot last season in Sydney.

"I was trying to not over-pump myself - I have a few matches against Top 10, Top 15 players and I was over-motivated," Kasatkina told WTA Insider after the match. "I was playing excellent in the first part of the first set, and then my focus went down, so I was just trying to keep myself on the same level. 

"I was just thinking it was a regular match, just regular quarterfinals of some tournament."

Kasatkina played a dominant tiebreak in the opener after failing to serve out the first set at 6-5, and won three of the last four games of the match after Wozniacki got the second set back on serve.

"She just won the Australian Open, and since I beat her, it means I was playing really well," Kasatkina said on-court after the match. "I was just trying to play point-by-point and focus on the rally."

The No.8 seed was stretched all the way in her upset bid, as she was forced to save a break point as she served for the match, but closed out the victory in stunning fashion, passing Wozniacki with a forehand winner after she drew the Dane in with a delicate backhand dropshot.

"It's important for the confidence, of course," said Kasatkina to WTA Insider after her second World No.1 scalp. "At the same time, if you want to achieve something, you have to beat the best players. If you want to be the best, you have to beat the best.

"The first time I beat No.1 in the world, I was so excited. I don't feel something unbelieveable, I'm just thinking about the next match."

The 20-year-old Russian repeats her run to the semifinals in St. Petersburg, having done so in last year's edition, and recorded back-to-back victories for the first time this season with the upset.

Kasatkina drew out 35 unforced error from the World No.1's racquet in the victory, as the usually reliable Wozniacki came off second-best to the Russian's variety in extended baseline exchanges.

Her serve also came through for her for the majority of the tighest moments, as she served nearly 70% of her first serves in, and won over 65% of the points played behind both her first and second deliveries.

Kasatkina will face defending champion and No.4 seed Kristina Mladenovic for a spot in the  final, who defeated Katerina Siniakova, 6-4, 6-3 in the quarterfinals.