Evergreen winger Ryan Giggs bundled home six minutes from time to rescue Manchester United from defeat at Celtic and send the Champions League holders to the brink of a place in the last 16.
Only an unlikely set of results, including a four-goal win for Aalborg at Old Trafford next month can rob Sir Alex Ferguson's men of qualification.
But it would have been very nervy indeed had Giggs, who celebrates his 35th birthday this month, not been on hand to finish from close range after Artur Boruc had failed to hold Cristiano Ronaldo's stinging shot.
It was tough luck on Celtic, who mounted a brave second-half resistance as United pressed.
However, Scott McDonald's precise lob came too early to allow the Scottish champions to cling on, leaving them only able to claim a moral victory and the possibility of a UEFA Cup consolation prize.
Two years ago United dominated with a swagger, only to be rudely shaken out of their stride by Shunsuke Nakamura's astonishing late free-kick.
Ferguson's men began in the same manner again as befits European champions. This time the unexpected shock came much earlier.
Set-pieces would have been a more likely route to goal had Jan Venegoor of Hesselink or Giorgios Samaras been fit but the Bhoys had enough height and muscle to make life uncomfortable for United.
Such was the desperation to clear their lines when Nemanja Vidic headed away Shaun Maloney's free-kick that Scott MacDonald was left on his own 10 yards out as Gary Caldwell nodded the ball back into the United danger zone.
Ben Foster was left in no man's land and McDonald's lob looped over his head and dropped neatly into the visitors' net. It was the first European goal United had conceded since they lifted the trophy in Moscow.
The ear-splitting noise was only to be expected given the willingness of Celtic's fans to get behind their team facing opponents that had dismissed them convincingly at Old Trafford a fortnight ago.
With Dimitar Berbatov and Wayne Rooney consigned to the bench, United's attempts to get level centred around Cristiano Ronaldo.
But for once, the prospective world player of the year was overshadowed; exclusively by men wearing green and white hoops.
Apart from McDonald, Barry Robson impressed. Caldwell and captain Stephen McManus were rocks in defence and Scott Brown simply dominated midfield.
One Ronaldo free-kick fizzed over for the visitors but other than that, the nearest they came in the first half was through Rio Ferdinand and John O'Shea.
The fact they are both defenders said much about Celtic's marshalling of United's forward line.
In contrast, Foster was keeping busy. On his Champions League debut and only second appearance for United, he would probably would have wanted plenty of action anyway.
He was not disappointed as Celtic peppered him with crosses and shots that were dealt with in fluctuating degrees of comfort.
Celtic returned to a scarf-holding home crowd desperate for more.
Ferguson, so keen to do well in his native city, had already made his assessment of the opening period by bringing on Berbatov for Nani, shifting Giggs to the wing - where the United manager had said he would not return.
With Berbatov pulling a few strings, there was definitely a more measured approach from United.
The problem was, with something to hold on to, there were Celtic bodies throwing themselves at anything even vaguely threatening.
One such instance came just before the hour when Vidic steered a Giggs corner into the path of Berbatov in the middle of a crowded penalty area.
The Bulgarian astutely turned the ball goalwards, only for Maloney to boot it off the line.
Celtic were creating a vastly-reduced number of chances but Caldwell saw a glorious opportunity for a second go begging when he nodded Maloney's corner over.
As the cacophony increased in the stands, so did the frenzy down below. With 20 minutes left, into the fray for an unhappy-looking Tevez was sent Rooney.
The pattern was already set. United attacks, Celtic clearances. Ronaldo broke it by needlessly kicking out at Brown by the touchline. None of the officials spotted it but UEFA might take a look.
No-one will need to have a second viewing at Ronaldo's next contribution though as his wickedly swerving shot had Boruc flapping.
The Celtic keeper meekly pushed it into the air, offering Giggs the easiest of close-range tap-ins, much to Ferguson's relief.Reuse content