Current world number one Novak Djokovic is planning to hold on to that title at the ATP World Tour Tennis Finals at London’s O2 this week. He needs to win all his round robin matches to head off Roger Federer, who has won more tour matches than any other player this year, be it not a Grand Slam title.

Novak has won seven slams, including this year’s Wimbledon and he’s held the No 1 spot in the ATP ranks for a total of 119 weeks. His current doubles ranking is 554 – obviously not a priority for him!

He does however have an Olympic medal, winning bronze for Serbia in the singles at Beijing.

Novak is excellent with his supporters and always takes time to stop, sign, smile for snaps. He has always been very complimentary about my sketches and really liked this one, showing it to his support staff before signing it on the opening Sunday at the O2. “You have a rare talent, Sir,” he said.