The teenager had shown the promise of being a future major winner with a run at Wimbledon back in 2019.
And yet at the same event this summer just a few weeks ago, she came off court at a loss to explain a dramatic dip in form as she went out in the first round.
But much like with Emma Raducanu back in 2021, it proved another teen fairytale of New York as Gauff recovered from looking out of sorts in the opening set to defeat Aryna Sabalenka, 2-6, 6-3, 6-2.
Afterwards, she said: “It means so much to me. It feels like I’m a little bit in shock.”
It was her father who first brought Gauff to the US Open to watch her idols, the Williams sisters, as a young girl. In the immediate aftermath in the same Arthur Ashe Stadium, she was quick to hug her parents in emotional scenes as well as Brad Gilbert, who was recently added to her coaching team and clearly to good effect.
It was Gilbert who had shouted “fight, fight, fight” as the American lost the opening set and looked somewhat disconsolate as she trudged back to her seat.
That opener saw a series of breaks as Sabalenka flitted from successfully hitting a serious of huge groundstrokes to finding herself rattled by a particularly partisan crowd, who were briefly silenced at the point she won the opening set.
It proved a ragged start to the second set by both players but it was Gauff who got the first break this time to go 3-1 clear. Where previously she had appeared folorn, suddenly she was rejuvenated.
That rejuvenation was as much down to Sabalenka’s error count as it was to her opponent raising her game. This wasn’t quite a vintage final with neither player quite finding their ‘A’ game at the same time.
But cruciailly it was the home favourite who produced the goods at the key moments as the match wore on.
At set point in the second, she tried to whip up the crowd as if to ask for more noise, and they duly obliged when she won the next point.
Again, she got the early break in the third set but, try as Sabalenka might, she could not force her way back into the tie.
There is scant consolation for the Belarusian that she will become the new world No1 on Monday when the rankings are revised on a night that belonged solely to Gauff.