EASTBOURNE, Great Britain -- Belarusian Aryna Sabalenka picked up the first Top 10 win of her career, rebounding from a 1-4 deficit in the third set to shock defending champion and No.2 seed Karolina Pliskova of the Czech Republic, 6-3, 2-6, 7-6(5) and advance to the Nature Valley International semifinals on Thursday.

"After the match I was thinking, 'How I did it?'" Sabalenka exclaimed, during her post-match press conference. "I was down 4-1, and there was no chance for me because my game was like totally died, I would like to say. I was so happy. It's good start of the grass season."

The rising 20-year-old had lost her first three matches against Top 10 players, but finally broke the duck with an astounding array of aggressive shots to outlast the reigning titleholder in two hours and 12 minutes. Each player won 100 points during the tightly contested barnburner.

World No.43 Sabalenka finished the match with 40 winners and 39 unforced errors, a solid ratio for her risky play. 7th-ranked Pliskova had 32 winners, but also 35 unforced errors in the encounter, and her vaunted serve never quite clicked consistently, with only 58 percent of first serves in the box on the day.

"On grass, it's so difficult to play against [Pliskova] because she's a big server," said Sabalenka. "It was so tough on her serve game, because I [would] just stand on the return and just think, 'Come on, just try to put the ball in and then just run.'"

"I cannot answer you, because I don't know how I did it," Sabalenka concluded, with a smile.

Sabalenka will face Poland's Agnieszka Radwanska in the semifinals, in their first meeting. Radwanska, who won the Nature Valley International ten years ago in 2008, dispatched No.5 seed Jelena Ostapenko of Latvia in straight sets earlier on Thursday.

"I never played against [Radwanska], and her game is really, really tough because she's a good runner," Sabalenka mused. "She read the game, like touch player...So it will be a tough match."

Sabalenka made her presence known from the very start, breaking for a 2-0 lead on her fourth break point of that game. Pliskova was able to level the match at 2-2, but the Czech never looked to be in command during the opening set, and Sabalenka continued to blast winners, getting back on track with a hold for 3-2 after a scorching backhand.

The Belarusian again went up a break after the next game, reaching break point with a powerful forehand winner, and converting the opportunity with an atypical backhand drop shot. Serving at 4-2, Sabalenka knocked off two consecutive forehand winners from deuce to blast her way through a tricky game and hold for 5-2.

Pliskova saved two set points by bludgeoning serves before holding for 5-3, but Sabalenka reached a third set point on her own delivery in the next game, and the unseeded player picked up the opening frame with a solid serve that was returned wide. Sabalenka had one more winner than Pliskova in the set, while the Czech had 15 unforced errors to Sabalenka’s 10.

But the momentum shifted heavily to the defending champion in the second set. After a number of closely contested games which nevertheless went with serve, Pliskova claimed a crucial break to lead 4-2 after Sabalenka self-destructed with a handful of miscues, mainly off the backhand side.

Pliskova improved her first serve percentage dramatically in the second set (83 percent, up from 53 percent), and the greater accuracy sent her soaring to a 5-2 lead. Sabalenka reached game point to hold for 5-3, but the Belarusian double faulted there, and then pushed a backhand long to give Pliskova set point. The Czech took that chance to level the match at one set apiece.

The World No.7 not only ramped up her serving efficiency during that set, winning 16 of 20 points on her first delivery, but had 10 winners to only three unforced errors during that timeframe.

Pliskova dropped serve with a double fault in the opening game of the deciding set, but after that blip, the titleholder started cruising. She broke Sabalenka twice and reeled off four straight games, holding for 4-1 with a backhand winner. At this point, the Czech’s experience seemed to be the deciding factor.

But Sabalenka continued to pressure the Czech, running down everything Pliskova threw at her. The Belarusian used her improved defense to break back for 4-3, and, suddenly, the match was again on serve. There were no more break points in the tilt as the players inexorably moved into the decisive tiebreak.

Sabalenka credited a coaching time out at 4-1 with her end-of-match fightback. "[The coach] said, 'If you lose, lose in a good way. I mean, like, just fight. Give some chance to play shots, because you're always missing from the first ball.'"

"He said, 'Just keep fighting. There's only one break. So just keep going. Try your best and just try to put the ball in, because it's a lot of mistakes.' Before that 4-1, was a lot of mistakes for me."

In the tiebreak, a brutal backhand winner by Sabalenka gave her an early 3-1 lead, but after the change of ends, Pliskova ended a grueling rally with a forehand crosscourt winner to pull back to 4-3. After an unforced error from the Sabalenka forehand wing erased another of her leads and leveled the tiebreak at 5-5, the match was still wide open despite being achingly close to the end.

Sabalenka blasted a backhand winner to reach 6-5, the first match point for either player. The serve went back to Pliskova, and after an exchange of groundstrokes, the defending champion sent a forehand mistake wide, giving Sabalenka a milestone win in her career.