Manchester United paid the price for complacency and fielding a weakened side and crashed to a shock Champions League defeat to FC Copenhagen.
Marcus Allback is mobbed after scoring the winner
Former Aston Villa striker Marcus Allback poked home the winner after 73 minutes to leave United still with work to do to reach the knockout phase.
And Sir Alex Ferguson's side had only themselves to blame for a lacklustre approach and a host of missed chances.
John O'Shea and Wayne Rooney both wasted easy opportunities to score.
The scale of Copenhagen's win was emphasised by the fact that Allback's strike was their first goal in the Champions League proper and their first win - sparking wild celebrations at the final whistle.
United's mystifying attitude was typified by Ferguson's team selection, making six changes from the side that demolished Bolton in the Premiership on Saturday.
And it showed in a disjointed first 45 minutes.
Copenhagen threatened after 23 minutes when Michael Silberbauer tested Edwin van der Sar low down at his near post.
And there was a scare for United four minutes later when Rooney went crashing painfully to the turf after a challenge by Brede Hangeland, who was booked by referee Wolfgang Stark.
But he recovered quickly to have United's best chance so far, a shot on the turn inside the area that rolled tamely wide.
Ferguson made a tactical switch of personnel at the interval, sending on Rio Ferdinand for Nemanja Vidic.
United were not at their best, but dominated after the interval and had opportunities to emphasise their superiority.
Ole Gunnar Solskjaer shot straight at Jesper Christiansen - although Copenhagen had a chance of their own when the unmarked Atiba Hutchinson headed wastefully off target.
O'Shea and Rooney were then both guilty of bad misses as United continued to let their limited Danish opponents off the hook.
Rooney set up O'Shea after 55 minutes, but he sidefooted wide with the goal at his mercy.
And Rooney was the culprit eight minutes later when he guided Gabriel Heinze's perfect cross wide from only eight yards.
Copenhagen were on the back foot, but when they were offered the chance to take advantage of United's generosity, they accepted the invitation gratefully to take the lead with 18 minutes left.
United failed to clear a corner, and when Hutchinson's header landed in the six-yard area, Allback poked home at the second attempt.
The growing frustration in United's ranks was shown when Cristiano Ronaldo was shown the yellow card for dissent.
United substitute Paul Scholes almost restored equality with six minutes left, but Christiansen raced quickly out of goal to block his attempted lob.
Ronaldo had the ball in the net with seconds left, but United's night was summed up when it was ruled out for offside.
FC Copenhagen: Christiansen, Jacobsen, Hangeland, Gravgaard, Wendt, Silberbauer (Kvist 71), Linderoth, Norregaard, Bergvold (Berglund 67), Allback (Thomassen 89), Hutchinson.
Subs Not Used: Gall, Pimpong.
Goals: Allback 73.
Man Utd: Van der Sar, Brown, Vidic (Ferdinand 46), Silvestre, Heinze (Evra 80), Fletcher (Scholes 71), Carrick, O'Shea, Ronaldo, Rooney, Solskjaer.
Subs Not Used: Kuszczak, Smith, Richardson, David Jones.
Ref: Wolfgang Stark (Germany).