A fight of almost five hours for this last quarter-final in Melbourne.
Yet led two sets to zero, Daniil Medvedev, world number two relied on a big first ball to catch up in the game.
And it all started with a tie-break.
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The match could have ended much earlier if Félix Auger-Aliassime had not cracked in the most important game of the match.
The Canadian lost 2-7 in the decisive game of the third set and the trend was reversed.
Daniil Medvedev revives in the match.
After saving a match point at the end of the 3rd set, the Russian finally won 6-7, 3-6, 7-6, 7-5, 6-4 in 4h42 of play. He will face the Greek Stefanos Tsitsipas, knocker of Jannik Sinner in three sets, for a place in the final.