Jannik Sinner recovered from a slow start against world number 173 Tristan Schoolkate to keep his Australian Open title defence on track.
Sinner, who claimed his first major title in Melbourne last year, had not dropped a set since October's Shanghai Masters.
But Australian Schoolkate thrilled a partisan crowd on Rod Laver Arena when he struck at 5-4 to win the opener and end Sinner's 29-set winning streak.
However, the wildcard could not keep pace with the top seed as Sinner sped through the gears to grab a 4-6 6-4 6-1 6-3 victory and a place in the third round.