The Italian second seed romped to a 6-1, 6-4, 6-2 victory in just one hour and 49 minutes against the shell-shocked wildcard on Rod Laver Arena.

Sinner plays big-serving Eliot Spizzirri, the 85th-ranked American, next as he pursues a Melbourne Park hat-trick.

Should he win three titles in a row in Melbourne, Sinner would join Novak Djokovic as the only men in the Open era (since 1968) to do so.

"Every match is very difficult, so very happy to be in the next round. Very happy with my performance," Sinner said in his on-court interview.

Addressing the crowd, he said: "You have been very fair to me, so thank you very much for the support.

"I feel I am in good shape at the moment," he added.

"The body feels good and the mind is in a good moment.

"This is a very special court and very special tournament for me."

The 34-year-old Duckworth was outclassed from the off, Sinner ploughing through a one-sided first set in just 26 minutes.

Ranked 88 in the world, journeyman Duckworth made a better fist of it in the second set in taking a 2-1 lead as they stayed on serve.

Duckworth grimly held when under severe pressure on his serve but buckled in the seventh game as the 24-year-old Sinner upped the ante.

Any semblance of resistance from Duckworth was broken and it was just a matter of time after that.

Sinner's chief rivals, world number one Carlos Alcaraz and 10-time Australian Open champion Djokovic, had already sealed their places in the third round.