Cashley Costs Chelski BigA comical own-goal by Michael Essien saw Chelsea drop crucial points as Reading twice came from behind to snatch a point at Stamford Bridge.
After scoring late winners in their last two games, the champions this time put through their own net with five minutes remaining.
Didier Drogba's double - his 18th and 19th goals of the season, had looked like putting Chelsea a point clear of United - who kicked off against Wigan at 3pm.
In a tight tussle, the Ivory Coast striker broke the deadlock seven minutes before half-time, holding off Marcus Hahnemann to nod in Frank Lampard's corner.
The visitors deservedly drew level when Leroy Lita stayed just onside and stooped to head in Glen Little's cross.
Drogba headed in Shaun Wright-Phillips' cross 18 minutes from time but a mis-hit clearance from Ashley Cole struck team-mate Essien, leaving Hilario stranded and earning Reading a point.
Blackburn 1-0 Liverpool
Bellamy endured an unhappy return to Ewood ParkLiverpool surrendered third place after missing a glut of chances against Blackburn at Ewood Park.
The home side ran out 1-0 winners thanks to Benni McCarthy's 10th goal of the season, the South African turning in Morten Gamst Pedersen's cross shortly after half-time.
But goalkeeper Brad Friedel was the man of the match against his former club, inflicting the Reds' first defeat in eight Premiership games and boosting his own side's survival hopes.
Bolton 2-1 Newcastle
Newcastle's Ramage heads past his own keeper to level for BoltonBolton and Portsmouth took full advantage, both winning 2-1, against Newcastle and West Ham respectively.
The Trotters came from behind to win at the Reebok Stadium.
Kieron Dyer netted for the second straight game to put Newcastle ahead but a Peter Ramage own goal and in-form Nicolas Anelka turned the game.
Portsmouth, meanwhile, saw Linvoy Primus score his first goals for exactly two years to inflict Alan Curbishley's first.
Ronaldo shines in United win.Cristiano Ronaldo emerged from the bench to spark a second-half triumph as Manchester United surged four points clear at the Premiership summit with a 3-1 win over Wigan.
After a goalless opening period, Ronaldo put the Red Devils in front with his first touch after being introduced as a half-time substitute, nodding home Paul Scholes' corner 69 seconds after the re-start.
The Portugal winger then blasted home the rebound after Chris Kirkland had saved his penalty and Ole Gunnar Solskjaer lashed home a third before Leighton Barnes netted a late spot-kick for Wigan.