World No. 1 Novak Djokovic was hit in the head with a water bottle following his second-round victory at the Internazionali BNL d’Italia in Rome, Italy, on Friday.

The 36-year-old Serbian was signing autographs for spectators when he was struck by the water bottle, tournament organizers told CNN.

Officials said Friday that Djokovic had returned to his hotel and that “his condition is not a cause for concern.”

The incident was an accident, organizers said, and provided video showing the bottle falling out of a spectator’s backpack.

Djokovic later posted on X, formerly Twitter, thanking fans for their messages.

“This was an accident and I am fine resting at the hotel with an ice pack. See you all on Sunday,” he said.

Djokovic defeated Frenchman Corentin Moutet 6-3 6-1 and is next scheduled to face Chile’s Alejandro Tabilo on Sunday.