MELBOURNE, Australia - No.15 seed Ashleigh Barty came back from a set down against former World No.1 Maria Sharapova to seal her spot into the Australian Open quarterfinals - the first Grand Slam quarterfinal of her career.

Sharapova, who won here in 2008, was looking for her first quarterfinal in Melbourne since 2016 after ousting Caroline Wozniacki, the defending champion, in three sets last round.

But she ran up against an on-fire Barty, the home favorite who came into the fortnight on a high after recording her second consecutive Sydney runner-up finish.

Read more: Steely Sharapova dethrones Wozniacki in Australian Open epic

After playing imperious tennis in the first set, Sharapova couldn’t maintain her level as Barty roared to life on Rod Laver Arena, battling through the last two sets to win 4-6, 6-1, 6-4 in just under two and a half hours.

"Maria was never going to go away," Barty acknowledged in press. "Proven champion. Time and time again it proves she will fight until the last point.

"I have never quite played in Rod Laver when it's been that full, I think. Especially against a champion like Maria who has proven it time and time again that she can come back from any deficit. She's proven herself in the biggest stages. It's pleasing."

The first set was a tense affair, with both players equally matched and the first eight games of the set going to the server, their contrasting styles on display as they felt each other out - Barty’s variety up against Sharapova’s power hitting.

But the tension ratcheted up to 100 as the set progressed, with Sharapova creating break chances at 4-3 and Barty at 4-4 but neither player finding a way to convert. Finally it was the former champion who broke through at a critical point at 5-4, before serving it out methodically and sealing the set with an ace.

Sharapova couldn’t sustain the quality in the second set, and Barty pounced on the letdown to edge her way back into it. Barty, who had made 22 unforced errors in the first set, tidied up her game considerably and regained her famed variety go grab her first break at 3-1.

She rattled off the next nine games in a row in clinical fashion to leave Sharapova reeling, opening up a double break to lead the final set 4-0.

But with her back against the wall, Sharapova dug deep to produce some of her best tennis. She put her double faults behind her - she struck 10 in the match and exactly half of those come in the third set alone - and gritted out her first hold of the set to get her name on the scoreboard at 4-1, and then notched a monumental break back to cut down on the Aussie’s lead.

Barty got tighter and tighter as Sharapova piled on the pressure, but the No.15 seed held firm to deny Sharapova two more break points - which would have leveled the match at 4-4 - and instead found another gear to keep her nose in front. She needed four match points as steely Sharapova made her earn it, but she finally sealed the match with her sixth ace to book her spot into her first ever Grand Slam quarterfinal.

"I thought she played a really great match, and I still had my chances which I didn't take," Sharapova said afterwards. "I definitely had a letdown for many games straight, gave her that confidence, and she's a confidence player, as well. And she'll take it. She's not going to back down."

The victory also marks a big milestone for Australian tennis: Barty is the first woman in ten years to reach the Australian Open quarterfinals, after Jelena Dokic's run in 2009.

"These are the moments we train and we practice and prepare for," Barty said. "You know, sitting down with my team late last year, it was one of the goals we set out that we wanted to go deep into slams, and I feel like that was the next step for me.

"It's amazing that it's happened in Australia and is happening in Australia. I have given myself the opportunity and the chance to play in front of the best crowd in the world on one of the best courts in the world and in my home slam. There is absolutely nothing better."

Up next for Barty will be a rematch of the Sydney final: she takes on No.8 seed Petra Kvitova in the quarterfinals after the Czech dismissed American youngster Amanda Anisimova in straight sets earlier in the day.

"It's exciting that I get to have another chance at Petra straightaway," she said. "Not often does that happen where you get to kind of have a replay against the same opponent.

"[I have to] win a couple more important points, I suppose, compared to Sydney."