Roger Federer and Novak Djokovic square off soon in the final big men's tennis match of the year, with the Swiss great bidding for a seventh ATP Tour Finals title.
Also at stake in London's O2 arena are bragging rights, Federer having lost the world number one ranking to the Serb last week.
Federer effectively handed the world number one ranking to Djokovic when he decided not to play in the recent Paris Masters, and Djokovic will end the year as number one, regardless of the outcome this morning in London.
