Roger Federer is a general 2/1 favourite for the ATP World Tour Finals after the draw was made on Tuesday.
The five-time champion has been drawn with Rafael Nadal in the group stages, having beaten the Spaniard in last year’s final.
Nadal can be backed at 11/2, which makes him the fourth-favourite with the layers.
Andy Murray is an 11/4 chance to end the season on a high after he was drawn with injury-troubled world number one Novak Djokovic, who is as big as 5/1 with Bodog.
Sky Bet are one of several firms who rate Federer the most likely winner, and their Chris Kennedy said: “The draw looks fairly equal with both groups looking similar in strength.
“There are some interesting re-matches from last week with Murray keen to get a swift revenge on Paris conqueror Tomas Berdych and Tsonga looking to avenge his final defeat to Federer.
“The fans will also be treated to a tasty Federer v Nadal group encounter.”
Coral are one of those offering the best price about Murray at 11/4, with the Scot as short as 9/4 in places following what many see as a good draw.
Their David Stevens said: “2012 has undoubtedly been Novak Djokovic’s year, but the world number one has been struggling with his fitness since the US Open.
“By contrast, Roger Federer heads to the O2 in great form, having won back-to-back events in Basel and Paris, and is a worthy favourite in our book.”
William Hill also go 11/4 about the British number one and Rupert Adams commented: “On current form it is difficult to choose between Federer and Murray but Roger was sublime last week and he is the favourite.”
If there is to be an upset the market suggests that last week’s beaten finalist Jo-Wilfried Tsonga might be the one to provide it. The Frenchman ranges from as short as 8/1 with Betfred to Sky Bet’s standout 14s.
Tomas Berdych, who knocked Murray out of the Paris Masters, is a 22/1 chance with bet365 while David Ferrer is out to 45/1 with Paddy Power.
The same firm offer a standout 90/1 about Mardy Fish, who completes the eight-strong line-up.