Fast-rising star, Coco Gauff has defeated Naomi Osaka to reach the fourth round of the Australian Open.

Gauff, 15, defeated the defending champion 6-3, 6-4 in the Rod Laver Arena, a match touted to be the beginning of a tennis rivalry between them.

Their previous and only meeting was at the US open which was won by Osaka.

"I don't know where that came from," the American said after the match.

"Honestly, like, what is my life?"

"Two years ago I lost in the first round in juniors and now I'm here," Gauff added.

"I was telling myself one point at a time and keep fighting. You never know what happens on this court."

Gauff will now face American Sofia Kenin or China's Zhang Shaui in the fourth round.