Daniil Medvedev will take on Stefanos Tsitsipas in a second straight Australian Open semi-final on Friday.
The pair met at the same stage on the Rod Laver Arena last year, with Medvedev winning in straight sets.
The Russian battled from two sets down against Canada's Felix Auger-Aliassime to set up a repeat meeting with the 23-year-old Greek Tsitsipas.
Tsitipas, who had elbow surgery last last year, powered past Italy's Jannik Sinner in straight sets.
In the first semi-final, 20-time Grand Slam champion Rafael Nadal will face Wimbledon finalist Matteo Berrettini.
Medvedev still the favourite
As the highest seed standing, Medvedev is arguably still the favourite to lift the title on Sunday, but was made to work hard for his semi-final berth.
Medvedev, who is trying to reach a second consecutive Australian Open final said after his quarter-final win: "I said 'I am going to make him work.'
"I managed to raise my level and when they closed the roof I was able to go through momentum and I started playing better."
Tsitsipas made up for his fourth-round struggle in five sets against Taylor Fritz to deliver a clinical performance against Sinner.
The Greek started the year in pain during the ATP Cup following little preparation after his operation, but has come into form in good time, as he plays in a fifth Grand Slam semi-final.
Nadal eyes history with Berrettini in his way
After another injury-ridden season, a rusty couple of performances at the Mubadala World Tennis Championships and contracting Covid-19, few would have predicted Nadal would be a factor in this year's tournament.
Yet the Spaniard has carved his way through the draw, and faces Berrettini for the second time in a Slam semi-final, having beaten him in straight sets at the 2019 US Open.
Nadal had to fight past a feisty Denis Shapovalov in the quarter-final and was taken the distance, while Berrettini had to make it count against another Spaniard - Carlos Alcaraz - in the third round.
Both men have been tested, but while Berrettini is looking to make a second final in two years, the end-game for Nadal is now tantalisingly close - to overtake both Roger Federer and Novak Djokovic for 21 Slam titles.
To reach the final, Nadal will have to beat a top 10 player for the first time since 2017, while Berrettini has lost all his six of Grand Slam clashes with top 10 players.
The Australian Open is Nadal's second most successful Grand Slam event in terms of matches won, but his least successful event in terms of titles won.