MELBOURNE, Australia - No.30 seed Anastasia Pavlyuchenkova pounded 71 winners to make her way into her sixth Grand Slam quarterfinal, and third at the Australian Open, with a thrilling 6-7(5), 7-6(4), 6-2 upset of No.17 seed Angelique Kerber in two hours and 37 minutes.

The Russian's record in the fourth round of majors is now a remarkable 6-1, with her only loss coming in her debut at that stage to Francesca Schiavone at the 2010 US Open. The Australian Open was the last of the four Grand Slams where Pavlyuchenkova reached the last eight - but has gone on to become the 28-year-old's most successful, with today's result marking the first time she has made quarterfinals in consecutive years at any of the majors.

Afterwards, Pavlyuchenkova credited her "attitude, fight and spirit" for her positive start to the year. "I was there pretty much every point - I mean, I tried to," she explained. "That always, I think, pays off - or at least that gives you some sort of confidence. Sometimes there were some moments or matches where I didn't feel my best or I didn't play my best, but I still was there."

This has been something Pavlyuchenkova has been working on with new coach Sam Sumyk in the off-season. "Sometimes before something I would go crazy and I would lose myself," she laughed. "Normally you prepare the match, you discuss with your coach. I would go and I would just go crazy. I will start doing something. He will be like, Well, hello. Where are you? You're just not here any more... We've been working on that. But also I want to change that myself, of course... I've been working so hard during the off-season, putting a lot of work in off the court and on court.

It's made for a newly "focused" and "disciplined" Pavlyuchenkova, in her words - but there's enjoyment in her tennis too. "I think I just find it more fun now," Pavlyuchenkova mused. "I like it. Like, I like these tough matches. I'm enjoying it. Before I think my game was always there, and I could come up with a lot of winners before, too. It's not enough. It's not enough just to play. Sometimes... you have to win somehow, find a way. I enjoy that sometimes, too. How many times you're not going to play your best tennis every match, obviously. Sometimes something is off. You just feel more tired or whatever. That's the part of the game."

Coming into the match, the pair had put together one of the most tightly contested rivalries in the upper echelons of the WTA Tour with seven wins apiece - and today's contest was fittingly close, with virtually nothing separating the two players for the majority of the clash. But Pavlyuchenkova, who had impressed last week with intelligent, tactically sound performances to take the net away from Taylor Townsend in the second round and to overcome a 0-6 head-to-head deficit against No.2 seed Karolina Pliskova in the third round, again kept a cool head to ride the ebbs and flows of a fluctuating scoreboard to emerge triumphant at the end. Her play was notable not only for her trademark power but for her ability to anticipate and counter Kerber in refusing to be outsmarted in trickier rallies.

Pavlyuchenkova's victory was all the more impressive given the manner in which the first set got away from her from a double break up. Holding break points in three of Kerber's first four service games and pressuring the German with the depth and weight of her returns, the Osaka and Moscow runner-up made a scintillating start - and it was her ability to switch up the play that was key in these stages. Pavlyuchenkova captured her first break with a judicious move forwards to tap away a volley, and conjured up delightful angles en route to breaking again for 5-2 - sealing the lead by going back to her trademark power as she hammered away a backhand return.

But Pavlyuchenkova was unable to put away a dogged Kerber, who hung in there with improved serving and greater aggression with her own forehand. Ill-advised dropshots both times Pavlyuchenkova attempted to serve for the set beckoned Kerber back into the set, and the 2016 champion needed little encouragement, reeling of four straight games as panicky errors began to creep into the former World No.13's game.

Down 5-6, Pavlyuchenkova's form lit up again, and a spectacular series of seven winners in a row put the 12-time WTA titlist in the driver's seat again with a a 3-0 lead in the tiebreak. But Kerber once again buckled down to chip away at the scoreboard - and after Pavlyuchenkova wobbled with consecutive forehand errors, the three-time Grand Slam champion slammed the door shut with a booming backhand winner on her first set point.

Having had the opening act stolen from under her nose, Pavlyuchenkova's resilience in the second set was commendable. The five-time major quarterfinalist raised her first serve percentage from 68% to 74% and once again maintained a positive ratio of winners to unforced errors, 26 to 17. Serving first, Pavlyuchenkova also managed to quickly move on from missed opportunities: Kerber would stave off two set points serving at 4-5, both with firm smashes, and another one at 5-6 with a glorious forehand winner.

But Pavlyuchenkova made sure to avoid any lapses on her own serve this time round, and would not have to face a break point during the entire set. Crucially, too, in redemption for letting her lead in the first-set tiebreak slip, she would maintain her focus for the whole of the second-set shootout, in which the Pavlyuchenkova backhand was the star of the show - finally finishing off the second act on her fifth set point with a pummeling return winner.

Riding her momentum into the decider and continuing to excel on the backhand side, Pavlyuchenkova quickly leapt out to another double break lead for 4-0. Kerber's defence seemed to be fading a touch, while a sprinkling of inopportune double faults did not aid the former World No.1's cause either. There would be one last fightback from Kerber, who came up with a magical forehand crosscourt angle to grab one of the breaks back - but, with Pavlyuchenkova limited her unforced error tally in the third set to a meagre seven, it would not be enough.

The Monterrey quarterfinalist immediately brought her forehand to bear to regain the double break for 5-2, and served out with the minimum of fuss, with her fourth ace finishing off the sixth-longest match win of the tournament main draw so far. Next up for Pavlyuchenkova in her bid to break through to her maiden Grand Slam semifinal will be another former World No.1, the resurgent Garbiñe Muguruza.

2020 Australian Open Highlights: Pavlyuchenkova fights past Kerber to make quarterfinals