Fearless Ukrainian qualifier Dayana Yastremska surged into a maiden Grand Slam quarter-final Monday, stunning two-time champion Victoria Azarenka at the Australian Open.

Driven by a booming serve and aggressive groundstrokes, the athletic 23-year-old battled past the Belarusian 7-6 (8/6), 6-4 on Rod Laver Arena.

Her reward is a clash with unseeded Czech Linda Noskova, who progressed to the last eight when Ukraine's Elina Svitolina retired with a bad back while trailing 3-0 in the first set.

"I need to take a little bit of time to breathe because my heart I feel is going to jump out of my body," she said.

"I always felt like I was running behind the train, but I think because I am a little bit of a fighter that's why I won this match."

Yastremska's previous best at the Slams was a fourth round appearance at Wimbledon in 2019, but she has been in impressive touch at Melbourne Park.

Ranked 93, she has beaten a number of top 50 players, including Wimbledon champion and seventh seed Marketa Vondrousova in the first round.

She landed the first blow in a rollercoaster opening set, going up 3-1, but 18th seed Azarenka responded to put it back on serve as Yastremska's error-count ballooned.

Her veteran opponent then broke again to move 4-3 ahead, but faltered badly serving for the set at 5-4, blown away to love.

Another break gave Azarenka a 6-5 advantage, but she again lost her nerve, with Yastremska saving two set points before sending it to a tie-break, where she prevailed after 74 draining minutes.

Azarenka flew 3-0 up in the second set, but her serve was again exposed and Yastremska came storming back, with a searing backhand down the line giving her a second break for 4-3 and she never relented.