Russian 16-year-old Mirra Andreeva registered a stunning 6-0 6-2 win over Ons Jabeur in the Australian Open second round on Wednesday.
The defeat meant that the sixth seed's bid to become the first Arab and African woman to secure a Grand Slam title suffered a setback.
Andreeva was in tears 12 months ago after losing the girls' final but was over the moon on her return to Rod Laver arena as she bagged her first top-10 win.
"Today when I saw that I play on Rod Laver, I said that this time I have to take my chance and I have to win on the big court for the first time and so I did," Andreeva told reporters.
The teenager said her win was probably one of her best performances even if she struggled with nerves at times.
"But I saw that she was nervous too," Andreeva added. "It kind of helped me, because I know I'm not the only one who is nervous before the match.
"I just decided to enjoy, because it's Rod Laver Arena and I'm playing against the person that I like. I decided just to play and I think I played okay."
Jabeur started the match with a big ace down the middle but quickly found herself on the back foot, as her young opponent made full use of some uncharacteristic errors to cruise through the opening set in 20 minutes conceding only eight points.
In her fourth Grand Slam main draw appearance since making her debut at last year's French Open, Andreeva showed maturity beyond her years as Jabeur desperately sought answers from her coaching team after the early jolt.
Jabeur — dubbed by fans as Tunisia's 'Minister of Happiness' — swapped her trademark smile for a more determined look and the 29-year-old held early in the next set but there was no stopping Andreeva, who raised her level again and pulled away.
Andreeva reached the Wimbledon fourth round last year and can match her best Grand Slam result with a win over Diane Parry next, but the world number 47 is not getting carried away with her success so far.
"I don't think that I've achieved something incredible," she said. "Sometimes when I'm lying in bed, I can overthink a little bit but the next morning I'm totally fine.
"I mean, I'm 16. Why do I have to think about the rankings?"
— Additional input from Reuters