BUDAPEST, Hungary -- 17-year-old Russian Anastasia Potapova emerged victorious in a grueling three-set battle with Sorana Cirstea, 6-4, 6-7(5), 7-5, in the quarterfinals of the Hungarian Ladies Open on Friday, setting up an all-teenager semifinal against No.8 seed Marketa Vondrousova in Budapest.

"[Cirstea is] a really tough player, she’s a huge hitter actually -- I’m also a hitter, so it was a very tough one for me," Potapova told the press, after the match. "Actually I was enjoying every second of this match, because I like playing the matches like these, because it shows you you can do whatever you want, you just need to push yourself over the limits and you can win."

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World No.87 Potapova, who made two WTA singles finals last year, rebounded from failing to serve out the match at 6-5 in the second set to oust former Top 25 player Cirstea. The Russian fired 42 winners to Cirstea's 25 in a hard-hitting, two-hour and 50-minute affair.

"The key was to just stay patient, to focus just on each point -- not even on the point, on the ball which I hit, on the technique," said Potapova. "When the score is 4-4 in the third set and you were playing for two-and-a-half hours already and you’re actually getting tired, your technique and movement and swings, you can lose it. So the key was just focus on these things and try to do the things right, not do a lot of mistakes."

Anastasia Potapova during her Hungarian Ladies Open quarterfinal match. (Credit: Peter Zador/Hungarian Ladies Open)

Potapova established herself early in the match, breaking to take a decisive 3-2 lead in the opening set, and refusing to cede that advantage despite numerous difficult games on serve as the set progressed. The Russian claimed the first set 6-4 once Cirstea sent a miscue wide on Potapova’s first set point.

Cirstea, however, jumped out to a solid 4-1 lead in the second set, as the former World No.21’s forehand began to accumulate winners. The Romanian had a break point to lead 5-1, but Potapova erased that chance with a barrage of groundstrokes leading to an overhead winner.

Subsequently, a litany of service breaks followed. Potapova got back on serve in the next game after Cirstea double faulted on break point, but the Romanian struck right back to grind through a long game and lead 5-3. Serving for the set, however, Cirstea quickly dropped her delivery again to allow Potapova back on serve.

The Russian broke Cirstea once more to lead 6-5 and serve for a straight-set victory. But Cirstea used powerful service returns to break Potapova and reach the tiebreak. A Cirstea backhand winner gave her a 6-3 lead and triple set point; Potapova saved the first two on her serve, but the Romanian snagged the second set after a Potapova forehand error on the third.

Potapova was the aggressor early in the deciding set, blasting an error-forcing service return on break point to claim a 2-0 lead. The Russian eased to 4-1, seemingly putting the narrow second-set loss behind her.

But Cirstea refused to yield, drawing level again to 5-5 as she maneuvered Potapova into errors. Serving at that juncture, Potapova nearly the game slip away with backhand errors, but the Russian was able to hold her serve on her fourth game point with an ace to lead 6-5.

Finally, Potapova crushed a backhand down the line in the next game to reach match point, and that would lead to the final blow as Cirstea sent an unforced error long to give Potapova the win.

Marketa Vondrousouva in action at the Hungarian Ladies Open. (Credit: Peter Zador/Hungarian Ladies Open)

Potapova will now face her former junior rival, the Czech lefty Vondrousova. "Tomorrow will just be a regular match for me, because my goal is a little bit higher," said Potapova. "But everything can happen, I just need to show my best tennis and then we will see. Maybe Marketa will go on the court and will do six aces in each game, so what can I do?"

Vondrousova beat Potapova in the first round of the US Open juniors in 2015. "[Vondrousova] was a real star at this moment, and for myself, it was my first Slam ever as a junior, but it actually was a good match," 2016 Wimbledon junior champion Potapova recalled. "I think [tomorrow] will be an interesting match and I’m very looking forward to it."

World No.81 Vondrousova had to get through a tussle of her own on Friday, coming back from a set down to beat Romania's Irina-Camelia Begu, 5-7, 6-1, 6-3 and advance to the final four in Budapest.

"I am very excited to be in the semifinals," Vondrousova told the media after her win. "I played yesterday like 2 hours 40 [minutes], so I was a bit tired, but I just kept fighting and I played a good match."

Begu claimed the lengthy opening set in 57 minutes with a service return that dribbled over the net for a winner on her third break point and set point of the 6-5 game. But Vondrousova shook that off and dominated the second set, winning all nine of her first-service points and firing eight winners to only two unforced errors during that timeframe.

Vondrousova zoomed to an early lead in the final set, breaking Begu at love for 2-0 and consolidating that break for 3-0 with an ace on her third game point. No further breaks of serve occurred in the match, as Vondrousova eased to clinching the set, finally holding at love for 6-3 with a forehand winner.

"I just kept fighting and believing I could play my game," Vondrousova exclaimed afterwards. "I was just fighting so much."

Defending champion Alison van Uytvanck will play in Saturday's second singles semifinal, as the top seed from Belgium won her eighth consecutive Hungarian Ladies Open match with a 3-6, 6-1, 6-4 victory over Kateryna Kozlova of Ukraine.

Like Potapova and Vondrousova, van Uytvanck also needed to outlast her quarterfinal opponent, edging Kozlova after just over two hours of play. The Belgian finished the match with five more winners and five fewer unforced errors than Kozlova.

Half of the deciding set's ten games went to the receiver before van Uytvanck held to close out the match and keep her title defense hopes alive.

No.1-seeded van Uytvanck will take on 5th-seeded Ekaterina Alexandrova in the final four, after the Russian downed No.3 seed Pauline Parmentier of France, 6-3, 6-2. Alexandrova was the only quarterfinal winner in under two hours, as she broke Parmentier five times out of nine opportunities during the clash.