Barty showed why she is the red-hot favourite to win the women's title as she ruthlessly despatched American Jessica Pegula 6-2, 6-0 on Rod Laver Arena.

The Australian will play Pegula's compatriot Madison Keys for a place in the final after she beat French Open champion Barbora Krejčíková of the Czech Republic 6-3, 6-2.

"I have grown as a person, as a player and I am more complete tennis player," Barty said.

"It is a credit to my team. 

"They have done so much work behind the scenes to make me the best version of myself.

"I'm absolutely loving playing out here. 

"It's been a lot of fun so far and hopefully there's a little bit more left."

Nadal, seeking a record-breaking 21st Grand Slam crown, emerged victorious from an ill-tempered five-set affair with Canadian Denis Shapovalov.

The Spaniard, whose only Australian Open title came in 2009, won 6-3, 6-4, 4-6, 3-6, 6-3 despite suffering with what appeared to be a stomach issue in the fourth set.

Shapovalov was unhappy with the time Nadal was taking between points and hit out at the umpiring after the match, claiming the Spaniard was "100 per cent" given preferential treatment.

"I think it's unfair how much Rafa is getting away with," the Canadian said.

"Of course - 100 per cent he does, 100 per cent. 

"Every other match that I have played, the pace has been so quick because the refs have been on the clock after every single point.

"I'm completely ready to play and the clock is ticking three, two, one, clicking towards zero.

"I'm looking at the umpire and obviously I'm going to speak up and say something.

"I've been ready to play for a minute and a half, and he tells me he's not going to give him a code violation because I'm not ready to play. 

"To me, it's a big joke if somebody says that."

Nadal's opponent will be Italian seventh seed Matteo Berrettini, who survived a fightback from French 17th seed Gaël Monfils to claim a 6-4, 6-4, 3-6, 3-6, 6-2 victory.