World number one Novak Djokovic
World number one Novak Djokovic will meet Switzerland's Roger Federer, his closest pursuer in the rankings, in the final of the World Tour Finals.
The Serb, who is unbeaten in four matches at this year's ATP Tour finale, is in his first O2 Arena final since the event moved to London in 2009.
He said: "Knowing it's the last match of the season, I'm really going to give my best physically and mentally."
Djokovic, 25, will finish 2012 as world number one regardless of the result.
He leapfrogged Federer in the standings after the Swiss decided not to play in the Paris Masters, sacrificing the ranking points he had secured by winning the event the previous year.
At stake, though, is Djokovic's 2012 head-to-head record against Federer. In their four meetings this year, each has won twice.
While Djokovic won in straight sets on the clay in the French Open and in Rome, Federer tasted victory in their two most recent meetings at Wimbledon and Cincinnati.
"I love playing against Novak," said Federer after beating Andy Murray 7-6 (7-3) 6-2 in their semi-final.
"We always have close matches, especially the last 10 or 15 matches which have been very back and forth.
"We both play aggressive tennis, we're natural attackers, that makes for exciting tennis.
"For both of us I think it's pretty straightforward - we've got to press out the juice that's left in our body and make it a successful year end."
Federer, who won 16 of the pair's 28 career meetings, first clinched the season finale in 2003, overcoming Andre Agassi in straight sets in Houston.
The 31-year-old has since won the event in five of the last eight years and is aiming to extend his record haul of titles to seven.
Although Djokovic has won the tournament only once, beating Nikolay Davydenko in the final of the event in Shanghai in 2008, the Australian Open champion insists he will not be disappointed if he fails to repeat that success.
"It's my first final here in London," he added.
"I'm really looking forward to it. It's already a great success."