RICARDO Carvalho's second-half header denied Manchester United a six-point lead at the top of the Barclays Premiership as Chelsea grabbed a deserved share of the spoils from a pulsating showdown at Old Trafford.
Louis Saha had cast aside the misery of his Champions League spot-kick miss at Celtic to put the hosts in front in superb fashion just before the half-hour.
But after Didier Drogba had escaped dismissal for elbowing Nemanja Vidic, Chelsea found their form in the second half - and Carvalho rose at the far post to power home Frank Lampard's far-post corner.
The result - which sees United retain their three-point cushion - was probably acceptable to both sides, although Sir Alex Ferguson will be less than pleased if the damage inflicted on Cristiano Ronaldo by Ashley Cole's late tackle proves to be serious.
Given what happened in the final frantic stages in Glasgow - where the Frenchman spurned a gilt-edged chance before his last-minute penalty failure, and Neil Lennon claimed Gary Neville told him Saha's "head had gone" before the spot-kick - there were major question marks over his ability to handle such a pressure environment. Yet it was soon obvious Saha was bearing no mental scars. The former Fulham man had proved himself a thorn in Chelsea's side long before he provided the precise finish to light the fuse for what had been a slow-burner of a game.
In signing his new six-year contract, Wayne Rooney has made it his stated aim to win the title with United this season - and the young England star played his part too with a brilliant final pass after he had taken control of Ryan Giggs' initial ball forward.
Saha quickly cut inside Carvalho on the edge of the area; then time appeared to stand still, and he waited for the moment to unleash the low shot which beat Carlo Cudicini at his right-hand post. The goal was just about deserved, because Cudicini had also been called on to tip a thunderous Ronaldo free-kick over as United pushed forward with zest.
By contrast, Chelsea were their usual measured selves but tested Edwin van der Sar only once during the opening period - Geremi forcing the Dutchman to punch clear with a snap shot.
In fact, the biggest imprint they left on the first half was through Drogba's elbow.Undoubtedly, the Ivory Coast forward has been one of the major stars of the domestic campaign. But there remains a sinister side to his game, and TV replays showed him looking back to check where Vidic was before he launched an elbow at the Serbian's face when the pair challenged for a high ball. Referee Howard Webb, who struck a good balance between allowing the competitiveness of the contest to prosper and clamping down on anything too reckless, did not get a clear view - and on the advice of the far-side assistant, he produced only a yellow card when a red might have been warranted.
Jose Mourinho made one of his famous half-time substitutions in an attempt to get his team to impose themselves more. The tactic, which saw Arjen Robben introduced for Geremi, worked as Chelsea set up camp around the United box.
But with Frank Lampard in one of his more profligate moods, failing to test Van der Sar with a hat-trick of chances and not beating the Dutchman when he did get one, it appeared the champions were about to slip six points adrift of their hosts.
The Stamford Bridge outfit have not won back-to-back titles by throwing in the towel when they hit trouble, though - and salvation arrived from an unexpected source when Carvalho rose to meet Lampard's far-post corner with a firm header which crashed in off the underside of the bar via the top of Saha's head.
Chelsea looked more likely to force a winner - but in truth, neither side came that close to getting one.
The sight of Ronaldo limping off late on after being caught by Cole will have brought a few worry beads to Ferguson's brow.
While United remain on top, the respective substitutes - Darren Fletcher and John O'Shea against Robben, Joe Cole and Paulo Ferreira - suggest an advantage in squad depth for Chelsea which will not be easily overcome.
