Title favourite Daniil Medvedev saved a match point before producing a stunning comeback against Felix Auger-Aliassime to set up an Australian Open semi-final against Greece's Stefanos Tsitsipas.
Second seed Medvedev eventually won 6-7 (4-7) 3-6 7-6 (7-2) 7-5 6-4, becoming the first player to fight back from two sets down in Melbourne this year.
Fourth seed Tsitsipas earned a dominant straight-set win over Jannik Sinner.
The 23-year-old, beaten by Medvedev in last year's semis, won 6-3 6-4 6-2.
Now Tsitsipas has the opportunity to avenge that defeat against the Russian and reach his first Australian Open final.
Source: BBC