But the snub was forgiven. The Centre Court crowd chanted: “Roger! Roger!” as the 37-year-old walked onto the court.
They cheered his every winning point and collectively groaned when Sonego had the temerity to display his own skills.
Those were not in evident abundance for the opening 20 minutes of his debut match at Roland Garros. The 24-year-old Italian went a double break down and Federer claimed the first set 6-2 in 26 minutes.
A similar fate befell the rookie in the second set and though Sonego clawed back one of the breaks, Federer did not squander his advantage. He held on to take it 6-4 and establish a two set lead in 63 minutes.
Federer, who won his only French Open in 2009, fluffed two break points at 2-2 in the third set. However he carved out two more chances at 4-4. The first went when a backhand slice floated long. But he converted his second with a backhand cross court winner to take a 5-4 lead.
Federer wrapped up the set and the win with his next service game. “It’s nice to be an outsider,” said the 20 time Grand Slam champion. “I am maybe a higher favourite at Wimbledon. But I’m very happy to get through my first round after playing someone I did not know.
“Sonego is fast on his feet and has got a nice forehand. I can see why he’s dangerous for a lot of guys on tour and not only on clay.”