World number 115 Kaia Kanepi produced one of the shocks of the tournament to send Aryna Sabalenka crashing out.
The 36-year-old Estonian saw three match points come and go but prevailed in the super tie-break to seal it; 5-7, 6-2, 7-6 (10-7).
Through to the quarter finals for the first time in her career, she will face Poland’s Iga Świątek. The 2020 French Open champion saw off Sorana Cîrstea in three sets.
The first set saw power tennis from both players out on Margaret Court Arena.
Kanepi held serve right up till 5-5, when Sabalenka turned the screw.
The Belarussian was pushed to deuce on her own service game but did enough to edge ahead.
She then applied enough pressure, opening up three break-points and only needing one, took the first set 7-5.
But the veteran Estonian roared back in the second set, nailing a huge break of serve to go 1-0 ahead.
Kanepi secured the double break, soon steaming ahead at 4-0 and eventually pocketed the set 6-2.
The 23-year-old from Minsk was beginning to look jaded in the deciding set, as Kanepi took an immediate break of serve.
She soon went 4-2 ahead but Sabalenka fought back for 4-4, as the set went back on serve.
Kanepi got the decisive break to move 5-4 ahead and serve for the match.
Nerves got to the Estonian, however, as Sabalenka saved four match points.
Three times at deuce, and on her third break point, Sabalenka levelled the set for 5-5.
Both players held serve, under enormous pressure, to send the match to a super tie-break.
Kanepi surged into a 5-2 lead but Sabalenka played clutch to level at 5-5.
It was soon 7-7, but the pressure got to Sabalenka, and Kanepi won three straight points to win the biggest match of her career.
Kanepi said she was shocked to have won. “Actually, I thought I was going to lose it after the match points I had on my serve.”
“It was really difficult to come back. I don’t know how I managed to do it.
“I was really tight. My hand was shaking when I started serving. I didn’t make any first serves in, and that added to the pressure. It was crazy.”