Unseeded Garbine Muguruza underlined her return to form by reaching the Australian Open semi-finals for the first time Wednesday, setting up a clash with fellow two-time Grand Slam champion Simona Halep.

The 26-year-old Spaniard, a former world No.1, defeated Russia’s 30th seed Anastasia Pavlyuchenkova 7-5, 6-3 in a hot and sunny Melbourne.

The other semi-final on Thursday sees top seed and home hope Ashleigh Barty face American 14th seed Sofia Kenin.

“Sometimes you don’t feel great but you’ve got to fight and stay there,” said Muguruza, now ranked 32 in the world, after reaching her first Grand Slam semi-final since Roland Garros in 2018.

“The first set was very hard, I think it lasted about an hour, but it was a very important set and I’m glad I got it.”

“I’m excited to play my first semi-final here. I’ve known her (Halep) for quite a long time so it's going to be a tough match,” she added.

Earlier, Halep powered into the semi-finals in 53 minutes with a 6-1, 6-1 destruction of Estonia’s Anett Kontaveit.

The 28-year-old Halep, the only quarter-finalist not to drop a set, is bidding to add the Australian Open title to her 2018 French Open crown and last year’s Wimbledon triumph.

“I felt great today on court. I was feeling my game, I felt strong on my legs,” said the red-hot fourth seed.

“I know how to play against her so I was just focused on every point I played.”

The Romanian lost the 2018 final in Melbourne to Caroline Wozniacki, but said: “That match wasn’t negative at all. I couldn’t finish (win) the match, maybe I was nervous.

Halep wasted no time asserting her authority over 28th seed Kontaveit, who was contesting her first Grand Slam quarter-final.

Halep broke the 24-year-old in the third game of the first set, then again in the fifth game. Spectators at Rod Laver Arena had barely had time to settle into their seats.

The former world No.1 sealed a one-sided first set in 29 minutes with a rocket of a forehand that the overwhelmed Estonian had no chance of retrieving.

Meanwhile, Roger Federer was fined $3,000 for using an audible obscenity during his quarter-final victory over American Tennys Sandgren, tournament organisers said on Wednesday. The Swiss was handed a code violation for swearing in the third set of Tuesday's match after the lineswoman reported Federer to Serbian chair umpire Marijana Veljovic.