Del Potro off the mark in Tour Finals

(GETTY IMAGES)

Argentina's Juan Martin del Potro put himself back in contention at the ATP World Tour Finals today, beating Spain's Fernando Verdasco 6-4 3-6 7-6 in front of another near sell-out crowd at London's O2 Arena.

The U.S. Open champion, needing a win after losing to Britain's Andy Murray when round-robin action got under way on Sunday, failed to take a match point at 5-3 in the decider and saw another slip away in the following game as Verdasco hung on.

He forged 6-1 ahead in the tiebreak, however, and this time made no mistake, securing victory when Verdasco hit a forehand into the tramlines.

Tournament debutant Verdasco is now relying on Roger Federer beating Murray in the evening match in Group A to keep alive his slim hopes of reaching the semi-final.