Day 7: Semi-Final: Nadal v Federer

Sue Barker introduces live coverage of the first semi-final from London's O2 Arena as the ATP World Tour Finals reaches the knockout stages. The injured Andy Murray reached the last four in 2012 but was knocked out in straight sets by Group B winner Roger Federer. Novak Djokovic, who emerged unbeaten from Group A, eliminated surprise-package Juan Martin del Potro in the other semi-final.