A ballboy at the Miami Open has been caught on the end of a Novak Djokovic tirade, with the world number one later apologising and saying the outburst was aimed at his coach.

The boy was giving a towel to the Serbian player during a break when Djokovic began screaming at his coach Boris Becker, snatching the towel from the boy.

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ESPN commentators said Djokovic was appearing to crack “mentally and physically” during the match against Scotsman Andy Murray, and had “frightened” the ball boy.

The referee gave the Wimbledon champion a violence for the outburst, which only angered him even more.

“What are you talking about man?! I was talking to my coach!” Djokovic yelled.

The referee told him the outburst “wasn’t a very good look”, with the young boy clearly scared by the rant.

The 27-year-old later apologised, blaming the Miami heat and the tough match against Murray, which he went on to win.

“When I lost the second set I yelled to my camp, to my box in frustration,” Djokovic said.

“Unfortunately the ball boy was in the middle of it and I really, really feel sorry and I regret that he was there.”

The new father also apologised to the parents of the boy and said he looked at the outburst in a new way after welcoming his first child in October.

“I sincerely hopes he forgives me. As a father, I wouldn’t wish that something like this would happen to my son.”

“Unfortunately sometimes emotions get the best of you.”