Federer and Nadal both tweeted their congratulations.

This was Djokovic's 30th major final — among men, only Federer has played more, 31 — and the first for Berrettini, a 25-year-old from Italy who was seeded No 7.

"Hopefully," Berrettini said, "it's not going be my last one." It was a big sporting day in London for his country: Italy's soccer team faced England at Wembley Stadium in the European Championship final at night.

With Marija Cicak officiating, the first female chair umpire for a men's final at a tournament that began in 1877, play began as the sun made a rare appearance during the fortnight, the sky visible in between the clouds.

The opening game featured signs of edginess from both, but especially Djokovic, whose pair of double-faults contributed to the half-dozen combined unforced errors. He faced a break point but staved it off.

"Definitely," Djokovic acknowledged, "felt slightly more nervous than I usually feel." The 6-foot-5, barrel-chested Berrettini's powerful serves sent line judges contorting to get their head out of harm's way. Djokovic occasionally took cover himself, crouching and raising his racket as if it were a shield to block back serves aimed at his body.

Not many opponents manage to return serves at 137 mph and end up winning the point, but Djokovic did that at least twice. And the big forehands Berrettini drives past most other players kept coming back off Djokovic's racket.

"I didn't play badly because I didn't feel well," Berrettini said. "He made me play badly." That's what Djokovic does: He forces foes to work so hard to win every point, let alone a game, a set, a match.