(CNN) -- Andy Murray claimed his second round-robin victory at the ATP World Tour Finals with an epic 6-4 6-7 7-6 win over Fernando Verdasco -- but the win was not enough to send him through to the semifinals at London's O2 Arena.
The British number one went into the match knowing a straight-sets success would secure his progress regardless of the result of the later match between Roger Federer and Juan Martin del Potro.
But, despite being under pressure on his serve for most of the match, Verdasco dug in to push Murray to the limit, leaving the Scot needing a Federer win to ensure the world number four made it through to the last four on Saturday.
As it happened, Del Potro won in three sets, and with all three players having won two matches -- with an indentical sets record of 5-4 -- it was Murray who missed out by virtue of winning games average.
Murray's serve had let him down in his defeat by the world number one on Tuesday and it was a similar story in the early stages here, the Scot struggling to land his first serve consistently and mixing aces with double faults.
The seventh seed had to save three break points in an eight-minute opening game and at 3-3 Verdasco snuffed out another opportunity with a second-serve ace.
The pressure finally told in the ninth game, however, Murray doing well to stay in a lengthy point and getting his reward when Verdasco missed the simplest of backhand volleys.
That left the world number four serving for the set, but his troubles returned as he opened the game with successive double faults. He dug himself out of the hole, though, and finally triumphed on his fourth set point.
Murray had history on his side, having beaten Verdasco seven times in their eight previous meetings, including in Valencia earlier this month, where he went on to take the title.
The second set was a story of missed chances for the 22-year-old, with Verdasco saving break points in the first and fifth games.
The Spaniard frequently has trouble matching power with consistency but a series of fine returns at 4-5 took the 26-year-old to his first break point -- a set point. But Murray did not wilt under the pressure, a big first serve salvaging the situation.
Verdasco was clearly frustrated to see the chance pass him by and Murray looked certain to break in the next game only for four more openings to go begging.
The Scot comfortably held to force a tie-break but he was always up against it after losing his first service point and a fourth double fault of the set from Murray gave it to Verdasco 7-4.
Another break point came and went in the opening game of the decider, Murray's tally now one taken from 13 opportunities.
The Spaniard was certainly giving away less cheap points but Murray's serving had improved and he was keeping his nose in front reasonably comfortably.
The home crowd urged him to break with Verdasco serving to stay in the match at 4-5 but the world number eight did not crack, and stayed cool two games later as he set up another tie-break.
The Spaniard had also served a lot of double faults, though, and one on the sixth point of the tie-break proved crucial as Murray finally wrapped up the win.
Murray told Sky Sports: "I thought it was an unbelievable match. It's probably the longest three-set match I've ever played."