WATCH: Novak Djokovic falls to knees as water bottle strikes head at Italian Open

Serbian tennis player Novak Djokovic was signing autographs for fans after a match at the Italian Open when an aluminum-type bottle hit his head forcing him to fall to his knees, Fox News reported.

Djokovic, 36, was treated for a head injury after after a bottle fell from the stands as he was interacting with fans following Corentin Moutet's, 6-3, 6-1, defeat on Friday.

The clang of the bottle could be heard after it struck both Djokovic and the ground, and an audible gasp from the crowd followed.

Djokovic fell to his knees, covering his head for close to a minute before being helped into the tunnel.

The Italian Open said Djokovic "underwent appropriate medication and has already left the Foro Italico to return to his hotel; his condition is not a cause for concern".

An alternate angle shows the bottle sliding out of a fan's backpack before hitting the tennis player's head.

Djokovic had a bump on his head and a bit of blood but did not require stitches, Italian Tennis Federation spokesman Alessandro Catapano said.

"Nole was taken to his hotel, and he seems OK. He was upset, but he seems OK," Catapano said.

The match was Djokovic's first of the tournament, and his first in nearly a month.

He is preparing to defend his title at the French Open, which starts May 26.