World No.1 Jannik Sinner has survived an almighty scare to keep his Australian Open title defence alive with a hard-fought win over local wildcard Tristan Schoolkate.

Sinner had his run of 29 consecutive sets won snapped by his 173rd-ranked opponent, but recovered to advance with a 4-6 6-4 6-1 6-3 victory on Rod Laver Arena on Thursday night.

It set up a third-round meeting with American world No.46 Marcos Giron, who outlasted Argentina’s Tomas Martin Etcheverry 7-5 3-6 7-5 3-6 6-4.

Sinner is attempting to defend his title with a doping saga hanging over his head, with a Court of Arbitration for Sport hearing set to be heard in April.

It comes after the World Anti-Doping Agency appealed against the sport’s decision not to ban Sinner, despite the Italian testing positive twice for the anabolic steroid clostebol in March.

Sinner’s problems were on-court early in Thursday night’s encounter, as Schoolkate took it up to his highly rated opponent.

The Australian broke to love in the decisive game of the first set and held his own serve until Sinner converted his first break point of the match in the seventh game of the second set.

After that Sinner took over, the two-time major winner’s class shining through as he dominated the third and fourth sets.

Sinner now boasts a 15-0 record against players at their home grand slams, including three against Australians at Melbourne Park.