Some 30-day challenges are more challenging than others. This one’s not so tough. In fact, to start with at least it could hardly be easier. All you have to do is pick a famous tennis champion and see if you can match their refuelling regime.

Sounds like a piece of cake, doesn’t it?

Only thing is, if you want to make the most of your month, it only makes sense to serve up the same sort of highly regimented, strictly controlled diet that the top two in the list live by. And bear in mind it takes a serious amount of work every day to burn off the 6,000 calories that make Novak Djokovic and Andy Murray such hot championship favourites for the US Open in August.

Six thousand calories is about two-and-a-half times an average man’s healthy intake. If you can take the challenge without putting on weight you will not only be seriously well fed, you’ll be championship fit as well.

Infographic - updated version