Novak Djokovic learns the art of being a ball boy

World number one Novak Djokovic takes time out after practice at the ATP World Tour Finals in London to learn the art of being a ball boy.

Over 1,600 youngsters applied for the 30 coveted positions and the 12 to 16-year-olds from all around the UK work hour-long stints throughout the day in five teams of six.