Men's title favourite Daniil Medvedev fought back from the brink of a shock exit on Wednesday to reach the Australian Open semi-final and keep his dream of a second Grand Slam crown alive.

Medvedev, the world number two, looked down and out as he lost the opening two sets to Canadian 21-year-old sensation Felix Auger-Aliassime before mounting a remarkable turnaround.

The Russian saved a match point at 4-5, 30-40 in the fourth set before completing an astonishing revival to beat the ninth seed 6-7 (4/7), 3-6, 7-6 (7/2), 7-5, 6-4 in a marathon 4hr 42min quarter-final that finished well after midnight on Rod Laver Arena.

The two players right after the match ended. Photo: AFP

Asked how he managed to win, the US Open champions Medvedev admitted: "I have no idea.

"I just fought to the last point and manage to raise my level."

It sets up a repeat of last year's semi-final against Stefanos Tsitsipas, which Medvedev won in straight sets before going on to lose to Novak Djokovic in the championship match.