“Of course, we need to improve, but I’m also happy, when you’re not playing your best tennis and win, it’s still a good result.”
With Sinner’s biggest rival Carlos Alcaraz injured and unable to compete either this week or in the upcoming French Open, the Italian is overwhelming favorite for every competition he enters in the weeks ahead.
Earlier, Croatian qualifier Dino Prizmic sent world number six Ben Shelton crashing out with a 6-4, 6-7 (4/7), 7-6 (7/5) victory.
Promising 20-year-old Prizmic, ranked 87th, secured his first ever win over a top-10 player in a three-hour battle in the Spanish capital.
American Shelton triumphed at the Munich Open on Sunday on clay but was unable to force a single break point on Prizmic’s serve.
Shelton’s compatriot Tommy Paul also suffered a surprise early exit, falling 7-5, 6-4 against Argentine Thiago Tirante.
Spaniard Rafael Jodar, 19, who impressed with a run to the Barcelona Open semi-finals last week, dumped out world number eight Alex de Minaur 6-3, 6-1.
“Everything went very well,” Jodar said.
“De Minaur is a very tough opponent, and I knew what I had to do from the very beginning.”
Women’s No. 2 Elena Rybakina scraped into the Madrid Open third round with a 4-6, 6-3, 7-5 win over Gabriela Ruse.
Kazakhstan’s Rybakina, who won the Australian Open in January and triumphed at Stuttgart last week, struggled in the first set, making 24 unforced errors to just eight winners.
After claiming a topsy-turvy second set, she came back from a break down in the third and sealed the victory on her third match point.
Rybakina will meet Zheng Qinwen, who produced a similarly battling performance to overcome Sofia Kenin, in the third round.
“Today, I basically survived,” said Rybakina after her hard-fought victory.
“It wasn’t the greatest performance but Gabriela, she played very well. She was playing very deep and aggressive, so it was very difficult.
“My serve was not really helping me today... but I’m really happy that I managed to win, and I hope I can bring better tennis next round.”
Last year’s runner-up and the third seed Coco Gauff made light work of Leolia Jeanjean with a 6-3, 6-0 victory at the Arantxa Sanchez stadium.
Gauff will take on Romanian Sorana Cirstea in the third round, after she defeated Tyra Caterina Grant in straight sets.
Fifth seed Jessica Pegula defeated Briton Katie Boulter 6-4, 6-4 in the late match on the main court to close out the day’s action.