Coco Gauff’s latest fairytale story at the Grand Slams suffered an unhappy ending as she lost to her fellow American Sofia Kenin in the fourth round.
The 15-year-old sprang to worldwide fame by reaching the same stage at Wimbledon before losing to Simona Halep.
But Novak Djokovic continued his bid to win an eighth Australian Open title by beating No.14 seed Diego Schwartzman.
The Serb will face big-serving Milos Raonic in the quarter-finals.
Roger Federer and world No.1 Ash Barty play in the evening session on Australia Day in the Rod Laver Arena.
Another fourth-round reality check for Coco
The world No.67 finally looked only 15 as she lost the decisive set 6-0 in only 33 minutes.
Gauff dropped her serve in the opening game of the match but fought back to win the first set on a tiebreak.
But Kenin, 21, targeted her forehand and took pace off the ball to force the teenager to generate her own pace to win 6-7 6-3 6-0.
Gauff served three double faults in one game in the second set, had her serve broken five times and made 48 unforced errors.
ESPN analyst Chris Evert said: “She lost to Halep in the fourth round at Wimbledon and she was a bit slower and mentally drained. And I saw the same thing in this match against Kenin. It is an emotional experience and she is not used to it.”
The No.14 seed Kenin, who broke down in tears after reaching a Grand Slam quarter-final for the first time, said: “I am so happy to be through to the next round. I tried not to let the pressure get to me.
“I tried to take it like any other match. I know she is playing well. I just tried to play my game and fight for every point and not focus on anything else.
“In the first set she played some really good points at crucial moments and I justed needed to calm down and relax and just fight.”
Gauff is still in the doubles with her best friend Caty McNally
Djokovic reaches his 46th Grand Slam quarter-final
Argentine Diego Schwartzman reached the fourth round without dropping a set before facing the defending champion. The Serb won 6-3 6-4 6-4.
Djokovic said: “Diego is a great quality player. I knew if I gave him time, he could cause a lot of damage from the back of the caught. I tried to mix it up and bring him forward.”
Next up is big-serving Milos Raonic.
“Quite a different match up from the match today,” said the world No.2. “He is one of the tallest and strongest physically with a big save.
“I have got to be ready for missiles coming from his side of the net. One of the key elements will be how well I return. When someone serves as well as him, it puts a lot of pressure on your return.
Milos Raonic is perfect
The world No.35 was the first man to reach the last eight after extending his perfect service record.
The Canadian has yet to be broken in this tournament and extended his streak to 59 successive games by beating his fellow former Wimbledon finalist Marin Cilic 6-4 6-3 7-5.
Raonic also sent down another 34 aces to raise another $3,400 (£1,758) for #Aces4BushfireRelief.
Asked about facing Djokovic, he said: “I think I am going to have to hit more than 34 aces.”
Petra Kvitova silences the Greek crowd
After the elimination of last year’s semi-finalist Stefanos Tsitsipas, Melbourne’s large Greek community got behind world No.23 Maria Sakkari.
She was bidding to become the first Greek woman to reach the quarter-finals of a Grand Slam but Petra Kvitova proved too strong as she won 6-7 6-3 6-2.
The double Wimbledon champion said: “I just kept playing. It is pretty tough to play Maria. Actually when I was shaking the hand with the umpire, I told him it was like a soccer match today.
“It’s nice on one side. On the other side, it’s tennis, and it’s not a Fed Cup. It’s strange but it didn’t bother me at all. It didn’t fire me up. I think my box fired me up!”
The No.7 seed is scheduled to meet Ash Barty, who plays later, in the last eight in a repeat of their Melbourne clash won by the Czech last year.
Tunisia’s Ons Jabeur is a shock quarter-finalist after beating Serena’s conqueror
The world No.78 beat Jo Konta, Caroline Garcia and ended Caroline Wozniacki’s career to become the first Arab women to reach the fourth round of a Grand Slam.
Now the 25-year-old is into the last eight after beating Qiang Wang – the Chinese No.1 who knocked out Serena Williams – 7-6 6-1.
“I am really, really happy with the way I played, especially the second set,” she said.
Jabeur, who had lost in the first round in her three previous appearances here, now faces Sofia Kenin in the last eight.
“Sofia is a really good player, a tough one,” she said. “Last time she won against me so maybe now it’s my revenge.”