Andy Murray has been "almost friendless" in the betting for the ATP World Tour Finals in London according to Sky Bet, who are offering 10/1 he wins five straight matches at The O2.

The Scot goes into the season finale in good heart after a recent title win in Valencia but a tough draw has given bookmakers the confidence to take him on.

Murray is 15/8 with Sky Bet to secure exactly four victories in the English capital, 10/3 for three, 4/1 for two, 5/2 just one and 10/1 to crash out with claiming a single success.

The same firm offer a top-priced 4/9 he opens with a win against US Open hero Juan Martin Del Potro on Sunday.

"Novak Djokovic and Roger Federer have been very popular on the outright betting, with Murray being almost friendless so far," said Sky Bet's tennis expert Chris Kennedy.

"The Scot faces a tricky first match with Del Potro and we are more than happy to take him on at the skinny price of 4/9.

"Del Potro has had an injury scare coming into the event but he has always troubled Murray in the past and we feel that he is solid value at odds against."

Del Potro is 11/5 at best with bet365, who offer 9/2 for a 2-0 upset and 11/2 the underdog prevails 2-1.

Murray is 5/4 at Sky Bet to oblige in straight sets and 10/3 with Boylesports for a 2-1 triumph.

Ladbrokes offer 2/1 Murray fails to qualify from his group and the same price he is beaten in the semi-finals, Sky Bet go 7/2 he finishes as runner-up and it is 17/4 at Expekt he is crowned champion.