American star Coco Gauff has staged a brilliant comeback at the Australian Open to advance through to the semi finals after beating Ukrainian Marta Kostyuk 7-6(6), 6-7(3), 6-2.
A marathon first set, which swung in momentum from one player to the other, was indicative of the way the rest of the absorbing contest played out as the fourth seed eventually emerged victorious.
Coco Gauff advances into the Australian Open semi finals after win over Marta Kostyuk
Gauff found herself in dire straits early on at Rod Laver Arena when she trailed Kostyuk 1-5 in the opening set, after she previously squandered all five of her break points.
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Yet despite Kostyuk holding a massive advantage in the set the pressure of the occasion got to her, as her service game fell apart to allow Gauff to claw her way back to parity.
The American then stole the set in a tiebreak that lasted almost 10 minutes for a bruising opening set win which stretched well past the hour mark.
The advantage looked to have killed any chance Kostyuk had of advancing past the quarter final stage with Gauff racing into a 5-3 lead in the second set.
Things looked grim for Kostyuk with Gauff boasting an incredible record in Grand Slams, having won 41 of 44 matches where she has taken the first set.
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However, she refused to go away and in a topsy-turvy clash, the Ukranian produced a vital backhand winner to hold off the American's charge towards a straight sets victory.
Almost inevitably a 36-shot rally then opened the tiebreak, which Kostyuk managed to get the better of before she kicked away to record a 7-3 win and force a deciding set.
Gauff fought back strongly to start the third, breaking her opponent's first service game and then consolidating the break with a tough hold as the match ticked over the 2 hours and 30-minutes mark.
The teenager broke Kostyuk once again in the third game, with the Ukranian slamming her racquet down on the court in a mixture of frustration and exhaustion as Gauff closed in on the win.
Kostuk prevented the bagel in the sixth game to delay Gauff's triumph by breaking her serve. But the resistance proved to be too little, too late as the American eased into the final four after over three hours on court.
Who will Coco Gauff play in the semi final of the Australian Open?
Gauff will face either world no.2 Aryna Sabalenka or ninth seed Barbora Krejcikova, who will meet in their quarter final clash later on Tuesday.
The American is scheduled to battle the reigning Aus Open champion or the Polish star on Thursday, January 25.
Meanwhile, on the other side of the draw, Linda Noskova will play Ukranian qualifier Dayana Yastremska, while Anna Kalinskaya will face 12th seed Qinwen Zheng for the remaining spots in the semis.