Murray, who was broken five times and let leads slip in both sets, will probably now need to beat world number one Novak Djokovic and in-form Czech Tomas Berdych if he is reach the last four at the O2 Arena.

Ferrer has had an impressive season, establishing himself as the leading player outside the top four, but Murray had won their previous four meetings including here last year and in back-to-back weeks in Tokyo and Shanghai last month.

The match quickly adopted a predictable pattern, with Ferrer drilling shots from the baseline while Murray attempted to knock his opponent out of his rhythm.

Murray got his reward with a break in only the third game, finally taking his fourth chance, but he promptly gave the advantage straight back with a loose series of points.

Murray has been in great form this autumn, winning titles in Bangkok, Tokyo and Shanghai, but he was struggling to get going today.

There were glimpses in the sixth game, not least a searing backhand pass that clinched a quite brilliant point, much to the delight of an O2 Arena that disappointingly was far from full.

The Scot, watched by good friend David Haye, was making life difficult for himself with a poor first-serve percentage and, when he did get a chance to break in the ninth game, he was made to pay for being too passive.

Murray appeared to be struggling with a leg problem and he was certainly not moving particularly well.

Suddenly Ferrer, who was playing a very solid match, was threatening the Murray serve to take the set. One chance disappeared with a wayward forehand but on the second it was the home hope who miscued.

Unsurprisingly, the trainer arrived to see Murray before the start of the second set, massaging and stretching out the world number three’s left leg and hip.

Ferrer, the most dogged of Spanish baseliners, is certainly not the player one would want to face when struggling physically but Murray received an immediate boost with a break in the opening game after his opponent netted the simplest of backhands.

Again the 24-year-old’s break did not last long, Ferrer winning four successive points on his opponent’s serve to level at 2-2, and Murray looked in real trouble when a mis-hit and net cord helped the Spaniard to two more break points in the sixth game, but this time he held on.

And in the next game he raised the pace to move a break ahead once more, only to give it straight back with a double fault.

It was a fascinating contest, if far from a great match, but Murray’s weakness on serve eventually proved the decisive factor as Ferrer brought up a first match point at 5-6 and took it with a backhand winner.