Image:Serbian superstar Novak Djokovic qualified in top spot and takes his place in Group A of the tournament
Image:Djokovic racked up and incredible 10,010 points after wins a Wimbledon and the most recent ATP Masters 1000 event in Paris
Image:Roger Federer has found his form once more and could even overtake Djokovic as world No 1 if he goes unbeaten at the O2
Image:Federer has picked up tour wins in Dubai, Halle, Cincinnati, Shanghai and Basel totalling 8,700 points. The Swiss star has been drawn in Group B
Image:Stan Wawrinka doesn't come in to the tournament in great form but is the reigning Australian Open champion
Image:Wawrinka has only won twice since the US Open but did pick up a win in Monte Carlo earlier in the year and at present has 4895 points
Image:Japan's Kei Nishikori will debut at the finals this year after a terrific year including reaching his first grand slam final at the US Open final
Image:Nishikori also picked up wins at Tokyo and Barcelona and has 4,625 points heading into his Group B fixtures in London
Image:Andy Murray left it late to qualify but an dominant sweep of wins in the final swing meant the Scot returned to the O2 with 4,475 points
Image:The O2 will have plenty to cheer about after Murray's wins in Shenzen, Vienna and Valencia helped him qualify
Image:In what was one of the most exciting qualifying seasons we've seen, Czech star Tomas Berdych made it after reaching the Paris Masters semi-finals.
Image:Berdych collated 4,465 points and was drawn in Group A of the competition.
Image:Milos Raonic goes into the tournament in great form although he was a beaten by Novak Djokovic in the Paris Masters final
Image:After a tour win in Washington Raonic head to the O2 with 4,440 points and will battle it out Group B
Image:Marin Cilic has been able to take it easy for the past couple of weeks after he qualified as a grand slam winner at the US Open
Image:The big-hitter from Croatia, who also won in Moscow earlier this year, has 4,150 points and will be in Group A for the finals