Teen sensation Andreeva stages sensational Australian Open fightback
She previously underlined her huge potential by crushing sixth seed Ons Jabeur in under an hour in round two and showed off her gritty fighting spirit to overcome France's Diane Parry 1-6, 6-1, 7-6.
Down 5-1 in the deciding set, Andreeva reeled off five games in a row to leave her in a position to serve for the match at 6-5.
Parry, herself only 21, halted the surge by breaking to set up a tie-break. But the young Russian had all the momentum and imposed herself again for a remarkable victory.
She will next meet either Czech ninth seed Barbora Krejcikova or Australian qualifier Storm Hunter.
Andreeva was out of sorts in the opening set, broken twice by Parry, who returned well and dominated from the baseline.
It was a different story in set two, with the Russian breaking in the fourth game with a passing shot before consolidating and breaking again on the way to levelling the match.
But Parry was unfazed and regained the upper hand with a break for 2-0 in the deciding set after a draining 16-shot rally.
She kept her cool to hold on through a 14-point third game and opened up a 5-1 advantage, seemingly destined for victory, only for Andreeva to surge back.
Ranked 47, the teenager made her Grand Slam bow at the French Open last year with a run to the third round after coming through qualifying, but it was at Wimbledon where she made waves, reaching the fourth round, also as a qualifier.
In her only other Grand Slam, she lost in the second round of the US Open to eventual champion Coco Gauff.
