(CNN)Ball kids -- and adults who do the same job -- are silent heroes at tennis tournaments.
Besides gathering and disbursing balls, they -- among other things -- fetch sweaty towels, hold on to umbrellas during changeovers in stifling heat and remove plastic sleeves from new tennis rackets. Most of the time they're unpaid.
One ball boy, however, was caught in the crossfire during Sunday's Miami Open final between Novak Djokovic and Andy Murray, leaving him startled and prompting the former to issue a public apology.
After Djokovic lost the second set, a furious world No. 1 barked loudly at his support camp and at the same time snatched his towel from the ball boy, who appeared startled before turning away.
Djokovic received a warning from chair umpire Damien Dumusois for the manner in which he yelled at his entourage -- not the way he grabbed the towel -- before regaining his composure and seeing off Murray 7-6 (3) 4-6 6-0.
Djokovic took to his Facebook page to say sorry to the ball boy in a video message.
"It's probably been the best start to a season aside from 2011 that I had in my career, and I can't be more grateful for all the support I'm getting from you guys and I'm enjoying my time playing and competing and hopefully I brought a smile to your faces," said Djokovic, who began 2011 with a 41-match winning streak.
"Also I want to reflect on a bad moment that happened in the final against Andy when I lost the second set. I yelled to my camp and my box in frustration," he added. "I saw the replay. Unfortunately a ball boy was in the middle of it and I really, really feel sorry and regret that he was there. There was absolutely no intention whatsoever to hurt him or scare him in any kind of way. I sincerely hope he forgives me. I really apologize."
A new parent himself -- Djokovic's wife Jelena and baby son Stefan accompanied him to both Indian Wells and Miami -- the Serb then apologized to the ball boy's parents.
"I do care about children a lot right now and I look at it in a much different way," he said. "So I want to apologize to his parents for this situation as well. As a father I wouldn't wish that something like this happens to my son. Again I sincerely hope you can forgive me and that we can move on. Unfortunately sometimes the emotions get the better of you.
"Also times as a professional athlete you learn how to control them and how to stay composed and mentally strong. But on a hot day like this when Andy was playing well and pushing all my buttons it wasn't easy."
Djokovic became the first player to complete the Indian Wells-Miami double three times, leaving him full of confidence as the tennis circuit shifts from hard courts to clay.
He'll now set his sights on trying to win a maiden French Open title and end the reign of nine-time champion Rafael Nadal.
"It's been a fantastic four weeks and I hope all of you guys will stay with me and support me during the clay-court season," said Djokovic.