Gabriel Agbonlahor's first-half header was the only goal of the game as Aston Villa stunned champions Manchester United 1-0 at Old Trafford.
Victory for Villa - their first at the Theatre of Dreams since 1983 and their first against United, home or away, for 14 years - propelled Martin O'Neill's increasingly impressive side into third place in the Premier League.
For United, defeat represented a huge missed opportunity to join Chelsea at the top of the table after the Blues had earlier dropped two points in a 3-3 draw at home to Everton.
Alex Ferguson's injury-hit side will now end the weekend three points behind the leaders following what was their first home defeat in the league this season.
The fitness crisis which hit United this week improved prior to kick-off with the return of Nemanja Vidic, Wes Brown and Wayne Rooney to full fitness, but Ferguson was still forced into fielding Darren Fletcher at right-back.
Otherwise, it was a strong United side that took to the pitch, although Ferguson will be concerned about a lack of end product that failed to break down an admittedly resolute Villa back line.
Villa took the lead in the 21st minute, Agbonlahor profiting from some excellent service from Ashley Young on the left hand side. The striker held the ball up before playing out to Young, whose eventual delivery to the near post was first rate.
Agbonlahor beat Tomasz Kuszczak to continue his impressive scoring record against United - he has now netted in each of the past four seasons against them.
The goal sparked a spate of chances at both ends before the break that amazingly failed to produce another goal.
Richard Dunne, the former Manchester City player, went closest for Villa when on 27 minutes he powered a header goalwards, only to see it blocked before it reached its intended target.
Three minutes later United had Kuszczak to thank for not going further behind, Edwin van der Sar's understudy reading Ashley Young's intentions perfectly as the Villa winger looked to square to an unmarked Emile Heskey.
At the other end, most of United's attacking promise came through the effervescent Rooney, although the England striker was largely frustrated by a lack of support during the opening period.
That frustration came to the fore in the 25th minute, when Rooney felt the need to take a dive in the Villa penalty area, ostensibly under a challenge from Luke Young. It was blatant and he was duly punished by referee Martin Atkinson with a booking.
Suitably embarrassed by his indiscretion, Rooney then seemed to embark on a personal mission to save face - and find a goal for United.
A clever flick moments later would have ended up in the back of the net had he made more contact with the ball - the lack of a firm touch nearly allowed Antonio Valencia to get to it at the back stick - but his best effort came just after the half-hour mark.
Rooney met Patrice Evra's cross with a deft touch that took him past Carlos Cueller before he hammered a shot that crashed off the underside of the crossbar and away to safety.
Rooney continued his assault after the break, but still to no avail despite the introduction of Michael Owen as a half-time replacement for Ryan Giggs. A shot just after the hour mark was well-blocked while moments later he opted for precision rather than power but Brad Friedel was equal to it.
Dimitar Berbatov was soon introduced as United ramped up their search for an equaliser and the best chance of the game was to fall his way in the 74th minute. But the Bulgarian, usually so adept at volleying, snapped at the cross and his effort from around the penalty spot skewed off target.
United dominated possession in the closing stages as they piled the pressure on Villa: Vidic had a header hacked off the line before Friedel was called into action again to deny Berbatov with just four minutes remaining.
But still they could not find a way through and Villa held on to register a famous win for both the club and their manager - it was the just the second time O'Neill has beaten United as a Premier League boss, after Leicester City's 1-0 win at Old Trafford in January 1998.