Top seed Kerber had no answer to Vandeweghe's power and aggression as the American charged into the quarter-finals with a 6-2 6-3 success on Rod Laver Arena.

While the world number 35 acknowledged her first triumph over a player at the top of the rankings was "that much sweeter" for having come at a grand slam, she revealed she had approached the match with confidence.

Asked if she was pleasantly surprised to have eliminated Kerber, Vandeweghe replied: "Pretty much every time I've been asked a question like this ... going out there and playing an opponent, any opponent, I go out there expecting to win.

"It's just another person that's in front of me, whoever it may be, if it's number one in the world, number 130 in the world, it doesn't matter; it's still an opponent to get in my way of achieving my goals."

Responding to a suggestion that Kerber may have been nervous, Vandeweghe said: "I can't really speak for her emotions and feelings. I can only speak for kind of how I played out there.

"I just felt like I was really executing my game well, keeping her on the back foot, and just kind of playing within myself. So that's what I felt was going on on the court."

Vandeweghe, who reached the last eight at Wimbledon in 2015, will now face Garbine Muguruza in her second grand slam singles quarter-final.

"It's an interesting match-up because she's an aggressor, as well," reasoned Vandeweghe. "She is going to play that way, and no other way.

"For me it depends on if I can match it, as well as if I can beat her to that punch of getting first strike, first play."