Kenin won 6-7 (5-7), 6-3, 6-0 to advance to her first ever Grand Slam quarterfinals, where she will face Ons Jabeur, who beat Wang Qiang in her fourth-round match.
After closing out the third set victory, Kenin dropped her racquet to the court and broke into tears, while an emotional Gauff received a standing ovation as she walked off the court.
“I’m just so speechless, I’m so happy,” said Kenin after the victory. “It was such a tough match.
“She had a great 2019. All respect to her, she played a great match. In the first set, she played some really good points at crucial moments.
“I just did the best I can, tried to take it like any other match. I tried to play my game, not focus on anything else. It means a lot — so happy to be through to the next round.”
An all-American affair
But in what was a battle of up-and-coming American players, it was Kenin who started the quickest.
She broke the 15-year-old in the first game but after falling into a 4-2 deficit, Gauff came roaring back, winning three straight games and took the first set in the resulting tiebreak.
After winning a back-and-forth second set, the world No.15 dominated the final set against a clearly tiring Gauff, completing the victory in two hours and nine minutes.
But the world No.67 was looking on the bright side despite missing out on her maiden Grand Slam quarterfinal appearance.
“I’m definitely going to savor this and continue to build and get better to work for moments like this, moments like that last match,” Gauff said. “Even today, even though I lost, I still had a lot of fun. I mean, now looking back, I’m not as disappointed anymore.”
“Even though I double-faulted today a lot, but my serve is definitely better. I think my return is better. I think I moved forward,” she said.
“I’m happy with how I moved, transitioned, like the baseline to the net. I’m happy how I’ve been doing that this week. It’s something I want to continue to improve on for my next tournaments.”
Elsewhere, home favorite and No. 1 seed Ashleigh Barty overcame American Alison Riske in three sets to reach the quarterfinals.
Defending champion progresses
He may not have been satisfied with the way he played at times, but defending Australian Open champion Novak Djokovic reached his 11th Australian Open quarterfinal with a three set victory over Diego Schwartzman.
The 16-time Grand Slam winner was clearly frustrated with some of his play in the first set, but eventually overcame the Argentine, finishing with a 6-3, 6-4, 6-4 win.
“It feels great. I had a fantastic couple of matches in a row, center court, last two rounds,” Djokovic said. “I felt more confident going through the ball, hitting serves really well.”
“Today was a good test because Diego was in form, he hasn’t dropped a set in three rounds. Obviously he can be a very dangerous opponent from the baseline if you give him time. I knew that,” he said.
“I stepped out on the court with a clear game plan what I need to do. I think I kept things pretty much in control in all three sets.”
The 32-year-old will face Canadian Milos Raonic in the next round, as he defeated 2018 finalist Marin Cilic 6-4, 6-3, 7-5 on Sunday.