CNN  — 

Teenager Coco Gauff stunned defending champion Naomi Osaka with a 6-3 6-4 victory to reach the fourth round of the Australian Open.

The 15-year-old American needed just 67 minutes to beat the No. 3 seed and set up a meeting with either China’s Zhang Shaui or compatriot Sofia Kenin.

Gauff was totally dominant for large periods of the match and perhaps even surprised herself with the ease of her victory.

“I don’t even know,” she replied when asked how she had pulled off that performance. “From the crowd, I guess. Honestly, what is my life, like, oh my gosh, two years ago I lost in the first round in juniors and now I’m here – it’s crazy.

“Honestly, I was just telling myself, ‘One point at a time and keep fighting because you never know what happens on this court.’

“I love it down here, oh my gosh, like, honestly, thank you guys from the bottom of my heart, like, oh my gosh, I’m on the Rod Laver Arena – I can’t believe this.”

Coco Gauff's father, Corey, was watching on as she shocked Osaka.

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On the same day that Serena Williams was shocked in the third round by Wang Qiang, this Friday at the Australian Open perhaps now marks a changing of the guard in women’s tennis.

Gauff had already beaten Venus Williams – who she also beat in the first round at Wimbledon – and the experienced Sorana Cîrstea to reach this stage and now adds Osaka to an ever-growing list of big-name scalps.

Her performance at this year’s Australian Open is all the more incredible when taking into account she is also continuing to study, though she says her teachers are giving her some special dispensation.

“Probably tomorrow,” she laughed when asked when she would next be doing homework. “Because I want to go to sleep tonight.

Naomi Osaka was unable to repeat her performance against Gauff at the US Open.

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“My teachers are giving me some time considering the circumstances – they’re letting me submit late.”

Last season, Gauff backed up her stunning grand slam debut at Wimbledon – where she became the youngest player since 1991 to reach the fourth round – with a third round appearance at the US Open, where she lost to Osaka.

How things have changed.

That day, Gauff won just three games in a one-sided match that ended with Osaka having to console the beaten teenager.

In October, she became the youngest WTA title winner for 15 years after beating 2017 French Open champion Jelena Ostapenko in Linz, Austria.

Despite her disbelief at being there, Gauff looks very much at home on the Rod Laver Arena and says her next goal is to finally meet the man it’s named after, one of tennis’ all-time greats.

“I walked past him a couple of times in the hallway but I never said ‘hi’ because I’m too nervous,” she said. “If he’s watching, let’s set up a meet up some time, I need a photo for Instagram.”