Murray has two more tournaments to play in 2011
Defending champion Andy Murray suffered a shock defeat by Argentine Juan Monaco in the second round of the Valencia Open on Wednesday.
Murray, the number one seed, was outplayed and despite a second-set revival he went down 6-2 3-6 6-2.
The Briton now heads to next week's Paris Masters, ahead of the season-ending ATP World Tour Finals in London.
Fernando Verdasco is struggling to qualify for London after losing to Gilles Simon in Valencia.
The Spaniard, seeded third, suffered a 6-1 6-3 defeat that leaves him ninth in the race to qualify for the eight-man event at the O2.
Number eight seed Gael Monfils booked his place in the second round in Spain with a 6-3 6-3 victory over Argentine Eduardo Schwank.
He doesn't usually make many mistakes and it's easy to lose against him if you are not on top of your game
Murray, 23, got off to a poor start as his second service game was broken to hand Monaco a 3-1 advantage. A double fault in the fifth saw Murray struggling before he eventually served out for 3-2.
He was soon 5-2 down when again his serve let him down, allowing a cool Monaco to take the set.
The second set began poorly for the Scot as he was immediately broken in the first game. He responded straight away by breaking Monaco to go 1-1, before establishing his authority and finding his serve to take the set 6-2.
The momentum was with the Briton heading into the third but Monaco was in no mood to roll over, his superior statistics on service and holding his nerve at key points giving him the upper-hand in the decider.
It did not take him long to break Murray and take a firm grip on the match and the Argentinian had victory in his sights with Murray serving at 5-2.
Murray started the game strongly but Monaco kept himself in it before going 40-30 for match point, holding his nerve to break the world number four again and move into the third round.
"Juan played very well," said Murray. "I know he's been injured for a while but today he proved that he is a great player. He played a very consistent game.
"He doesn't usually make many mistakes and it's easy to lose against him if you are not on top of your game."
Murray is still in the doubles alongside his brother, Jamie, and the pair take on Argentines Juan Ignacio Chela and Eduardo Schwank on Thursday.