Ashleigh Barty accelerated her march towards a maiden Australian Open title Tuesday with a straight-sets masterclass against Jessica Pegula, setting up a semi-final with Madison Keys.

The single-minded world number one dismantled the 21st-seeded American 6-2, 6-0 in 63 minutes on Rod Laver Arena to power into the last four at Melbourne Park for only the second time.

She will face the unseeded Keys for a place in Saturday's final after the American, ranked 51, upset French Open champion and fourth seed Barbora Krejcikova 6-3, 6-2.

Keys is into her fifth Grand Slam semi-final and her first in Melbourne since 2015.

But she faces a huge task against the top seed who is edging closer to becoming the first Australian woman to win her home Grand Slam since Chris O'Neill in 1978.

"That was solid tonight. I had a lot of fun out here. I was able to serve and find a lot of forehands in the centre of the court and I was happy to take the game on," said Barty.

"I've grown as a person, I've grown as a player, I feel I am a more complete tennis player," she added, referring to her first semi-final on home soil in 2020.

"I've obviously got a few more years experience under my belt in handling different situations and being able to problem-solve out on court."

The current Wimbledon champion has yet to drop a set and has only given up 17 games in her five matches at Melbourne Park.

So dominant has she been that when Amanda Anisimova broke her in the second set in their fourth-round match, it ended an astounding run of 63 consecutive service holds.

That break was a blip, with Pegula not managing to repeat the feat.

Pegula won the first three points and was serving for the opening game at 40-0, but Barty roared back to break when her opponent netted a backhand from the baseline.

She then slammed two aces down in her own opening service game to consolidate.

Pegula got on the board on her own serve and then pushed Barty to deuce four times in her next service game but could not break back.

One more service hold was as good as it got for the American who did not win another game from 2-3.

The Australian pounced again in game seven with Pegula netting a volley then a backhand to give her a double break for 5-2 before serving out the set with her fifth ace.

Barty put away a volley for an immediate break at the start of the second set as a fading Pegula, taking on a world number one for the first time in her career, was bullied around the court.

The pair had met once before, at Roland Garros in 2019 when the Australian went on to clinch her first major title.