Maria Timofeeva's dream run at the Australian Open continued as the No.170-ranked qualifier knocked out No.10 seed Beatriz Haddad Maia 7-6(7), 6-3 to reach the fourth round.

After triumphing in a 16-shot exchange to convert her fifth match point and seal her first win over a Top 20 player, the 20-year-old raised one fist to the sky in celebration at reaching the second week of a Grand Slam in her first main draw.

"Well, actually, in the third for me," Timofeeva quipped in her on-court interview. "If we count the qualies! But you're right, it feels like a fairytale."

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Making the most of the moment, Timofeeva was also quick to plug her Kiss My Ace YouTube channel, where she vlogs behind the scenes of her career, when signing the on-court camera.

Timofeeva is no stranger to unlikely runs. The Australian Open marks just her third tour-level main draw. In the first, last July, she pulled off a rare historic feat in claiming the Budapest title as a lucky loser.

"I always felt that I have something in my game that I can pursue," she said in her press conference. "If I'm in the right mental state, I can play good. So I think now is just everything coming up together."

The victory backs up Timofeeva's wins in previous rounds over Alizé Cornet and Caroline Wozniacki, and she's brimming with self-belief as a result.

"The matches against Alize, also the three matches in the qualifying, they gave me some confidence obviously," she said.

"Also, playing on the big courts. I got a chance to play on the big courts already in the qualifying because I was playing against Australian players [Astra Sharma and Priscilla Hon]. I think that was also one of the key moments because I was getting used to the stage, to the crowd, and had less pressure in matches today with Beatriz or the day before with Caroline." 

Timofeeva also had good reason to let it all out after getting over the line. Her well-rounded all-court game had been in full flow over the previous hour. After a slow start, she'd bounced back from a 3-0 first-set deficit to edge the first set, saving one set point, and to advance to 5-1 in the second.

Timofeeva had never previously faced an opponent ranked in the Top 50, but her smart shot selection and confident execution had kept her a step ahead of Haddad Maia -- particularly in rattling off a series of backhand scorchers down the line in the second set.

However, having held her first match point at 5-1, Haddad Maia was threatening an unlikely comeback, and Timofeeva required all of her resilience to close out the Brazilian. She will next face Marta Kostyuk, who defeated Elina Avanesyan 2-6, 6-4, 6-4. A first Grand Slam quarterfinal is on the line for both.