David Ferrer stretched his winning streak to 11 matches - the best run of his career - with a hard-fought 6-3 3-6 6-4 victory over Juan Martin del Potro at the ATP World Tour Finals.
After triumphing at the Paris Masters last week, the Spaniard showed his exhertions in the French capital had taken nothing out of him with a typically all-action display in London.
Del Potro certainly played his part in a see-saw contest that thrilled the crowd at the O2 Arena, recovering from a set down to force a decider with some scintillating strokeplay from the back of the court.
The opening set went with serve until the fourth game, a forehand down the line giving Ferrer two break points. He needed only one of them, though, as his opponent sent a volley well wide to fall behind.
Del Potro was also forced to work hard in his next service game, eventually coming out on top at the end of a 15-shot rally when facing the possibility of going 5-1 down. He at least made Ferrer have to serve out for the set.
It seemed the second set would follow a familiar pattern, too, as Del Potro had to absorb plenty of punishment from the opposite site of the net, hanging on to his serve during an epic third game that lasted over 11 minutes.
The fact he survived, however, seemed to galvanise him. Suddenly unfurling some heavy groundstrokes, the Argentinean went 3-1 up, then immediately consolidated the break by holding to love.
An ace sealed a 5-2 lead and after a forehand winner gave him a second set point in his next service game, Del Potro duly produced a delicious drop shot that even the ever-willing Ferrer couldn't retrieve.
The fourth seed from Valencia registered an early break in the decider thanks to a stunning cross-court winner, only for Del Potro to reply in kind thanks to some booming forehands.
Yet after fighting so hard to get back on terms, the sixth seed surrendered in rather meek fashion at crunch time. He lost his serve to love in the 10th game and never threatened to deny Ferrer what could prove to be a crucial win in Group B.