Win his match today against Rafa Nadal at the ATP World Tour Finals in London and British tennis ace Andy Murray will guarantee a year-end number 2 ranking and almost certainly book a semi-final spot.This all means that he will not be able to leave before Saturday evening or Sunday if he makes the Final. Why is this significant? Because he happens to have a Davis Cup Final against Belgium at the Flanders Expo in Ghent five days later, which will be played on clay and not the hard-court surface at the O2. Obviously having more time to practice on the ‘red dirt’ would be advantageous but I guess he’ll see plenty of it since he is likely to play on all three days of the premier international men’s teams event in order to win his first Davis Cup and Britain’s first since 1936. He trails Rafa 15-6 in the head-to head over eight years, but did beat him on the Spaniard’s favoured clay in Madrid in their only match this year. Their 2010 three-set semi was a real cracker with Rafa winning on the close final set tie-break. Given the one-sided matches at the Finals this year, which one sports writer called a ‘lingering malaise’, everyone’s hoping for a repeat of their match five years ago. Andy signed this sketch for me on his way into the O2 to practice last Saturday.