Top seed and reigning champion Angelique Kerber was bundled out of the fourth round of the Australian Open by big-hitting American Coco Vandeweghe yesterday, losing 6-2 6-3 on Rod Laver Arena.

The German world number one’s exit followed that of men’s top seed and world number one Andy Murray earlier in the evening on the same court.

The 25-year-old New Yorker claimed a place in the quarter-finals at Melbourne Park for the first time, blasting six aces and 30 winners to overpower Kerber.

“I guess I faked (having confidence) a lot because I was feeling like crap out there,” said the American.

“But, you know, ‘fake it till you make it’... my game plan was to execute knowing that she was going to get a lot of balls back.”

Vandeweghe, who celebrated her biggest career victory with a shrug of the shoulders, moves on to meet Spanish seventh seed Garbine Muguruza in the last eight.

“Last year I came here and didn’t even win a match and here I am now,” Vandeweghe added.

“It’s confidence having a full off-season with no injuries... last month I set a goal for this tournament to make the quarter-finals.”

Meanwhile, Venus Williams said she was not prepared to even countenance the suggestion she could potentially meet younger sister Serena in the final after she advanced to the quarter-finals with a 6-3 7-5 victory over Mona Barthel.

The 13th-seeded Venus had some struggles against the German qualifier but clinched the crucial points to advance to a last eight clash with Anastasia Pavlyuchenkova.

Serena, who has won 22 grand slam titles to her sister’s seven, is on the other side of the draw and faces Barbora Strycova in their fourth round clash today and has looked the most comfortable of the players left in the tournament.

As such, a potential ninth showdown in a grand slam final, and second at Melbourne Park, between the American sisters could potentially be on the cards, though Venus sidestepped the question after her victory over Barthel.

“That could hopefully happen,” the 36-year-old Venus said when asked of the possibility.

“We both still have to work very hard to get there. I’m going to be focused on winning one round at a time and focus on doing what it takes to be there.”