Day 4: Federer v Gasquet

Sue Barker presents live coverage of the group stages of the ATP World Tour Finals, which sees the top eight players in the world battling for the end-of-season honours in London. Andy Murray might be absent through injury, but there will be a stellar cast at the O2 Arena with the world's top two players Rafael Nadal and Novak Djokovic both in attendance. Djokovic is the defending champion, but Nadal is a world number one with something to prove - he's yet to win the event in five appearances.