From the
WTF website:
Roger Federer has pulled out ahead of the championship match at the Barclays ATP World Tour Finals due to a back injury. The six-time former season finale champion made the announcement to fans on Sunday at The O2 in London following the doubles trophy ceremony.
Novak Djokovic, his opponent in Sunday’s final at The O2 in London, will play a pro set (first to eight) against Andy Murray. The Briton will then team up with John McEnroe in a doubles exhibition match against Tim Henman and Pat Cash.
Federer wrote on his Facebook page, “I am sorry to announce that I cannot play the finals tonight versus Novak. I hurt my back late in the match yesterday against Stan [Wawrinka]. I am very disappointed and I hope to be feeling better soon.
“It’s been an extremely difficult decision because I love playing in London and the [Barclays] ATP World Tour Finals have been an absolute highlight of my career. Unfortunately, my back problem does not allow me to play right now. I hope all tennis fans and those involved in the event will understand."
All ticket holders who have purchased tickets from authorised ticket sellers will be contacted in the next 48 hours.