Seventh seed Matteo Berrettini fired 53 winners on his way to a 6-1, 4-6, 6-4, 6-1 victory over American wild card Stefan Kozlov in Melbourne on Wednesday.
The Italian, who suffered from stomach problems in the first round, showed little signs of injury during his two hours and 38 minutes on court.
“It was a tough match. I think I started really well but then he started playing better and I wasn’t feeling my strokes after the first set, but I am happy to be through,” Berrettini said.
“My stomach is better, but it is never easy to recover from something like that, so that is why my energy wasn’t its highest. I am really happy to win.”
Berrettini relied on his powerful serve to wear down Kozlov in the first set but the American came back strong in the second.
The Italian then used his court craft and combined it with some superb shots, forcing Kozlov into errors.
Having beaten American Brandon Nakashima in four sets in the first round he will next face another youngster in the shape of Carlos Alcaraz.