Coco Gauff knocks out defending Australian Open champion Naomi Osaka

Naomi Osaka's Australian Open title defence is over in the third round after her shock elimination by American youngster Coco Gauff.

Coco Gauff. Source: Associated Press

World No.4 Osaka fell to the 15-year-old 6-3 6-4 in front of a stunned Rod Laver Arena crowd.

The Japanese star was let down by 30 unforced errors with Gauff, playing in her first Australian Open, holding her nerve to wrap up the match in just over an hour.

Still at school, Gauff set up the win with a devastating serve while her ground strokes were fearless.

The last time the pair met was in the third round of the 2019 US Open, when Gauff only managed to win three games.

She broke former top-ranked Osaka to go ahead 5-3 in the first set before closing it out.

Gauff then broke again in the first game of the second before Osaka broke back thanks to two double faults by the youngster.

There was a sense that momentum was shifting back the champion's way - but it didn't last long.

Gauff, who trained with Serena Williams in the off-season, refocused to get another break to lead 4-3, which she was able to consolidate.

While a tearful Osaka couldn't get off the court quick enough, Gauff soaked up the win in front of the huge crowd.

"Two years ago I lost first round in juniors and now I'm here - this is crazy," Gauff said.

"Honestly, I was just telling myself one point at a time and keep fighting."

Gauff will now meet either American 14th seed Sofia Kenin or China's Shuai Zhang in the round of 16.