Striker Salomon Kalou headed a stoppage-time goal to give Chelsea a dramatic 1-0 victory at Watford on Saturday that cut Manchester United's lead back to six points and kept the Premier League title race alive.
With the regulation 90 minutes played at Vicarage Road, the championship looked destined for Old Trafford as United had earlier roared back from a goal down with half an hour left to crush Blackburn Rovers 4-1.
But Chelsea, winners of the last two titles, had Ivorian substitute Kalou to thank for a strike in the second minute of stoppage time that gave the Londoners 72 points to United's 78, with seven matches left to play.
In Saturday's opening game, Peter Crouch scored a hat-trick as Liverpool beat Arsenal 4-1 at Anfield to leapfrog the Gunners into third place on 57 points.
Down at the bottom, Sheffield United are only one point above the drop zone after losing 1-0 at Bolton Wanderers and Charlton Athletic beat Wigan Athletic 1-0.
West Ham United defeated Middlesbrough 2-0 while Manchester City edged towards safety with a 1-0 triumph at Newcastle United. A last-minute goal by Ian Pearce earned Fulham a 1-1 draw with Portsmouth.
Chelsea rounded off a pulsating day of action with a fine goal, Kalou meeting Andriy Shevchenko's cross with a well-placed header, and a priceless win.
Manager Jose Mourinho threw on extra attacking players in a desperate bid to break the deadlock but Chelsea lacked their usual fluency and struggled to create clearcut chances.
Ivorian striker Didier Drogba was denied by Watford keeper Ben Foster, on loan from Manchester United, in the first half and Germany midfielder Michael Ballack missed a great chance in the second.
Manchester United deservedly trailed to a 29th-minute Matt Derbyshire goal but second-half strikes by Paul Scholes, Michael Carrick, Park Ji-sung and Ole Gunnar Solskjaer secured a seventh successive league win.
Nemanja Vidic will be out for at least four weeks after suffering a serious shoulder injury. The long delay in treating the centre back seemed to affect United's concentration as poor defending of a Morten Gamst Pedersen cross allowed Derbyshire to knock in a loose ball.
FANTASTIC SUPPORT
United were transformed after the break and Scholes showed all his class and experience to level after 61 minutes when he burst past two defenders before producing a calm finish to beat keeper Brad Friedel.
Ryan Giggs then somehow hit the bar in front of an open goal but Carrick spared his team mate's blushes when he fired in the second in the 73rd minute.
Park tapped in the third seven minutes from time after Friedel failed to hold a Cristiano Ronaldo shot and substitute Solskjaer completed the comeback in the last minute.
"The great thing we showed was the composure to not lose our heads, keep our nerve and keep on playing and by doing that we kept on making chances in the second half," United manager Alex Ferguson told Sky Sports.
"The intensity of our game was absolutely fantastic but so was the support, that probably put us over the line today."
