Marta Kostyuk earns best win by ranking against Coco Gauff in Stuttgart quarterfinals

Just over a month after her first win over a Top 5 player, Marta Kostyuk earned her second on Friday at the Porsche Tennis Grand Prix with a 3-6, 6-4, 7-6(6) upset of No. 3 seed Coco Gauff in the quarterfinals.

The two-hour, 44-minute victory is the latest milestone in a 2024 season that has just kept getting better for the Ukrainian. In January, the 21-year-old advanced to her first Grand Slam quarterfinal at the Australian Open. In February, Kostyuk celebrated her first Top 5 victory when she rallied past Jessica Pegula in the semifinals of the San Diego Open. In March, the Ukrainian achieved a career-high ranking of No. 26 after putting together a semifinal run at Indian Wells. And this week in Stuttgart, Kostyuk has posted back-to-back Top 10 wins for the first time in her career—picking up her biggest win by ranking in the process.

Friday was a day for the underdogs in Stuttgart: Kostyuk's upset of Gauff closed a day that also saw No. 8 seed Marketa Vondrousova come from a set behind to beat No. 2 seed Aryna Sabalenka, and Italy's Jasmine Paolini nearly knock off No. 4 seed Elena Rybakina.

But Kostyuk's performance might've been the most valiant of all. Historically volatile when facing adversity on court, Kostyuk instead steeled herself facing a 6-4, 4-2 deficit to force a third set. In the decider, she rallied twice: from 3-1 down at first, and then, broke Gauff at 6-5 when it looked like the American was going to escape with a victory after saving three match points in the 10th game.

Four more chances to win came and went in the tiebreak after the Ukrainian led 6-2, but a pair of long rallies—most crucially, Gauff missing a forehand passing shot in the net at 6-6—helped push Kostyuk over the line.

It was also Kostyuk's first-ever win against Gauff, and reversed the result of their quarterfinal meeting in Melbourne, which Gauff won in a similarly-epic three sets after Kostyuk had battled back to force a final set.

To reach her third semifinal of the season, Kostyuk has logged nearly nine hours on court. In the second round, the Ukrainian saved a staggering five match points in beating Australian Open finalist Zheng Qinwen, 6-2, 4-6, 7-5—and that came only after she defeated former tournament champion and the always-tough-on-clay German, Laura Siegemund, in more than three hours in her opener.

For a spot in the final, Kostyuk will next face Vondrousova. The Czech won their only previous meeting in Billie Jean King Cup play last year, but the two were scheduled to play in the second round of Indian Wells before Vondrousova withdrew citing personal reasons. Kostyuk went on to reach the semifinals.