Jannik Sinner is still regaining focus on the tennis court after his three-month doping ban.

The top-ranked Italian overcame a brief lapse during the first set before claiming a 6-4, 6-2 victory over Dutch qualifier Jesper De Jong in his second match back on tour at the Italian Open on Monday.

Sinner jumped to a 4-1 lead but then lost his serve twice as the 93rd-ranked De Jong took the first set to 4-4.

There were poor drop shots, a double-fault and other errors from Sinner. However, he regained control in front of his home crowd with his powerful groundstrokes and big serve to extend his winning streak to 23 matches, dating back to October.

"I felt like I started the match very well and then I had a big drop," Sinner said. "I tried to understand what was going on. Then fortunately I broke him on 4-all again, which then gave me the confidence to continue."

Sinner advanced to the last 16 of his first tournament since winning his third Grand Slam title at the Australian Open in January.

Sinner will next face 17th-seeded Francisco Cerundolo, who beat Austrian qualifier Sebastian Ofner 6-2, 6-4.

Cerundolo is coming off a run to the Madrid Open semifinals and beating Nicolas Jarry – last year's Rome finalist – in straight sets in the opening round.

"Last time I played here, I lost against him here on this court," Sinner said, referring to a three-set loss to Cerundolo in the round of 16 two years ago. "It's going to be tough. For sure I have to raise my level if I want to play even. … I'm trying to understand where my game is so it's going to be a good challenge, good test for me."