Kerber crushes Keys to reach Melbourne Park semis

Making a mockery of the 21st seeding she landed after a miserable 2017, the former world number one outplayed Keys in almost every facet of the 51-minute match to seal a semi-final date with Simona Halep or Karolina Pliskova.

"I was just playing my game, I was not thinking a lot about winners or errors, I was staying in the moment and trying to play every single point," a beaming Kerber said on Rod Laver Arena.

"I just went out and played like I've been playing all week. Just playing my game and enjoying it. I'm just happy to get through and be here in the semis."

In an echo of her loss to compatriot Sloane Stephens in the final of last year's U.S. Open final, Keys appeared to be struck by stagefright and offered none of the power and accuracy that got her to the last eight without losing a set.

Keys started the match with three unforced errors and a netted backhand to lose her first service game and barely 15 minutes were on the clock before the German had another break in the bank and a 4-0 lead.

The 22-year-old tried charging the net in a desperate attempt to kickstart her game but a brilliant backhand pass from Kerber brought up two set points and the stanza was hers in 22 minutes when the 17th seed sent a forehand long.

The American briefly came to life to hold for 3-1 in the second set and then unleashed a couple of bombs to put the set back on serve on a Kerber error after a lengthy rally.

A 21st unforced error from the racket of Keys gave Kerber the break straight back, however, and the 30-year-old sealed her place in the last four with a third of the set when the American netted a backhand.

It has been quite a return to form for Kerber in Australia this year after she broke a 27-tournament title drought going back to her 2016 U.S. Open triumph in the Sydney International warm-up.

Kerber, who celebrated her 30th birthday last week, is now guaranteed to return to the top 10 in the rankings even if she goes no further at Melbourne Park.

"I'm really enjoying my tennis, I'm really enjoying being on court," she added.

"I am just happy actually."