U.S. Open champion Coco Gauff faced a significant challenge against Ukrainian world No. 37 Marta Kostyuk but triumphed 7-6(6), 6-7(3), 6-2 to advance to the Australian Open semifinals for the first time on Tuesday.
The fourth-seeded American, rarely playing poorly and still advancing, secured victory after over three hours on a scorching hot Rod Laver Arena, adhering to her coach Brad Gilbert's well-known mantra of "Winning Ugly."
"I'm really proud of the fight I showed today; Marta's a tough opponent. Every time we play, it's a tough match," she said. "Yeah, I really fought and left it all out on the court today."
Gauff, concluding her final Grand Slam as a teenager, had entered the quarterfinals on a nine-match winning streak, aiming to build on her first major success in New York last year.
Kostyuk aggressively challenged the American from the start, surging to a 5-1 lead and serving twice for the opening set, also holding a set point on Gauff's serve.
Recognizing the challenge, the 19-year-old American problem-solved on her feet, rallying to win five successive games and serve for the set herself.
"I was just trying to get one more game in the first set and make it more competitive. Then one game turned into another, and I was able to win that set," Gauff added.
Despite Kostyuk earning three break points off Gauff's forehand and forcing a tiebreak with an American double fault, Gauff capitalized on Kostyuk's missed opportunities to claim the set.
The second set saw both players trading breaks in extended rallies, with Gauff edging ahead and serving for the match at 5-3. However, a combination of Gauff's vulnerable second serve and Kostyuk's ability to produce winners allowed the Ukrainian to break back and level the match at one-set all.
In the third set, Gauff adjusted her strategy, intensifying the pace of her first serve and backhand as Kostyuk tired. Despite being broken when serving for the match for the second time, Gauff eventually secured victory on her third attempt.
She now moves into a semi-final against either Aryna Sabalenka, a rematch of last year's Flushing Meadows final, or Czech ninth seed Barbora Krejcikova.
