Elena Rybakina ended Iga Swiatek's bid for a third title at the Porsche Tennis Grand Prix on Saturday with a 6-3, 4-6, 6-3 victory in the semifinals. 

The 2-hour, 49-minute victory for Rybakina snapped Swiatek's 10-match winning streak at the tournament, and ensures that a new champion will be crowned at the Porsche Arena.

"It was a very tough match, like always, against Iga," Rybakina said after her latest win over the World No.1. "Really happy that I won on clay. Gives confidence, of course."

In the final, Rybakina will face unseeded Ukrainian Marta Kostyuk. After coming through three straight three-set thrillers earlier in the week, Kostyuk grabbed a straight-sets win at last, toppling No.6 seed Marketa Vondrousova 7-6(2), 6-2. 

Rybakina and Kostyuk have split their two previous meetings, which both came in 2023. Kostyuk won in three sets in Adelaide at the start of that year, but Rybakina exacted revenge with a straight-sets victory in the first round of that season's US Open.

Another final: Rybakina has now beaten a World No.1 player on five occasions, and four of those have come against Swiatek. The Kazakh is through to her fifth final of the season, and hopes to add a winner's trophy in Stuttgart to triumphs in Brisbane and Abu Dhabi. She was also the runner-up in Doha and Miami.

She's the first player to reach five finals in the season's first four months since Victoria Azarenka in 2012. 

How the match was won: Swiatek started the match as if on course to run her unbeaten streak in Stuttgart to 11. She opened up a 2-0 lead to start the first set, and had two break points for a 3-0 lead. 

From there, the match was played, more often than not, on Rybakina's terms. The Kazakh kept sustained pressure on Swiatek's serve throughout the match, and created 20 break point opportunities over three sets. While Swiatek saved 16 of them, the combination of seven double faults and 42 unforced errors played a part in the result.

"I think the return definitely improved from last year from both angles," said Rybakina. "Of course it depends on the opponent, a bit of the speed of the serve, and of course placement. But since we played with Iga many times, more or less I try to predict where she's going to go, and [I'm] really happy with the return and overall with the game."

Notable moments: Rybakina won five games in a row in the first set -- and had four set points to win a sixth. She eventually took a one-set lead on her fifth set point, after saving a break point that would've gotten the set back on serve. 

The second set went with serve for nine games, until Swiatek broke serve for the first time since the match's opening game to take it the distance. In the decider, the World No.1 saved the first eight break points she faced -- but the match turned on the ninth. 

Three straight games for Rybakina from 2-1 down (after Swiatek had swatted away sixth break points in the 1-1 game) gave her a lead she never relinquished.

Kostyuk's best plays in Stuttgart semifinal win vs. Vondrousova

Kostyuk conquers another seed: In the day's second semifinal, 27th-ranked Kostyuk claimed a 1-hour and 35-minute victory over reigning Wimbledon champion Vondrousova of the Czech Republic. Kostyuk is the first Ukrainian to make the Stuttgart final, bettering Elina Svitolina's semifinal run from 2021.

"I came here on Saturday and I practiced four days before my first match, and really I was playing worse and worse with every day," Kostyuk said. "I was like, 'OK, time to play some matches because I don't want to practice anymore.'

"In tennis, everything is very close. It's like you can really feel very bad but then have the best week of your career, like it happened to me. I think it's trust the process, really. I really excelled this week and I tried in every match to just do as much as I can, and yeah, things are getting better."

Before this week, Kostyuk had beaten four Top 10 players in her career, but never in back-to-back matches. Suddenly in Stuttgart, she has beaten three in a row, with her upset of Vondrousova following hard-fought victories over No.5 seed Zheng Qinwen and No.3 seed Coco Gauff.

Kostyuk had to save match points against Zheng in the second round, and she needed a third-set tiebreak and eight match points before closing out Gauff. By those standards, her semifinal win over Vondrousova, where she converted four of her seven break points, was a relative breeze.

The Ukrainian did not have it all her own way in the first set, where she led 5-1 and held three set points in that game. Vondrousova gritted her way back into the opener and pulled it all the way into a decisive tiebreak.

In the breaker, though, Kostyuk reclaimed her dominance, drawing errors with incredible speed before garnering four more set points at 6-2. Kostyuk made no mistake this time around, backing up a big serve with a forehand winner to seal the one-set lead.

Kostyuk never dropped serve in the second set as she wrapped up another upset. Kostyuk is now into her third career final and second of the year: she finished runner-up to Katie Boulter in San Diego last month, and she won her maiden title in Austin last year.