A mouthwatering finale to the men's tennis season ended before it even began when Roger Federer was forced to pull out prior to the ATP World Tour Final showdown with Novak Djokovic.
The 33-year-old Swiss, who spent nearly three hours beating compatriot Stanislas Wawrinka in a gruelling semi-final the day before, announced his decision on court as London's O2 Arena filled up for the expected final.
Federer, who was bidding for a seventh title at the year-ender, says he developed a back problem late in his match with Wawrinka.
He apologised to the crowd saying he wasn't "match-fit" after developing a back problem.
ATP president Chris Kermode, standing alongside Federer, then announced that Andy Murray, who failed to qualify for the semi-finals after being thrashed by Federer on Friday, would play Djokovic in an exhibition match instead.
Federer hopes to play for Switzerland against France in the Davis Cup final, which starts on Friday.