Wimbledon champion Angelique Kerber was knocked out of the Australian Open by world number 35 Danielle Collins in the biggest shock of the tournament.

The world number two was thrashed 6-0 6-2 in the fourth round in 56 minutes.

The German broke early in the second set but was immediately broken back and dropped serve a further two times.

Collins needed just one match point to break again at the end and claim a ruthless victory.

"I may not have won a Grand Slam match before this but, I've got to tell you, I think it's going to keep happening," said Collins, who has not gone beyond the first round in any of her five previous Grand Slam appearances.

Opportunity goes begging for Kerber

Collins' biggest result to date was a quarter-final victory last March over seven-time Grand Slam champion Venus Williams to become the first qualifier to reach the last four at the Miami Open.

She is relatively unknown on the WTA Tour after playing much of her tennis in the US college system.

Kerber, meanwhile, was among the favourites for the title and had dropped just 10 games in the previous three rounds.

The 2016 champion's draw was favourable and on paper the route to the final looked within grasp, largely thanks to some tasty match-ups among the other contenders.

Defending champion Caroline Wozniacki was knocked out in the third round by five-time Grand Slam champion Maria Sharapova, who was then beaten by Australian Ashleigh Barty.

Top seed Simona Halep will now take on seven-time champion Serena Williams in the quarter-finals on Monday, while eighth seed Petra Kvitova takes on home favourite Barty - meaning two more contenders will fall.

Kerber was beaten by Halep in the semi-finals at last year's Australian Open and will be disappointed not to have made it further this time around.