It took close to two and a half hours and three sets for Alexandrova to beat the four-time Grand Slam winner 7-6 (7/3), 4-6, 6-4. The victory sets up a quarter-final clash for Alexandrova against either American eighth seed Amanda Anisimova or Ukraine's ninth-seeded Elina Svitolina.

Sabalenka took an early 2-0 lead in the first set before dropping four games to concede the momentum. She fought back, making it 4-4 on a forehand drop volley winner. She failed to keep her opponent down, as double faults saw Alexandrova break through and win it 7-6.

In the second set, Alexandrova hit a forehand long to surrender a break and give Sabalenka a 4-3 lead. The top seed then held serve twice to force a decider.

Later, in the deciding set, the World No. 1 was broken when she netted a forehand to give Alexandrova a 3-1 edge, but the Russian double-faulted away a break in the seventh game. In the 10th game, Sabalenka made three unforced errors, giving Alexandrova a break and match points.

Sabalenka saved the first with a service winner and the second with an ace, but on her third match point, the Belarusian committed her sixth and final double fault to seal the loss.

"I didn't have any expectations before the match," Alexandrova said. "I knew it was going to be super difficult when I walked on the court.

"I was trying to risk as much as possible because it felt like it was the only way to create some chances. It caused many more mistakes, but at the same time I created many more opportunities."