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.
• Mourinho hails Carvalho class
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.
Mourinho hails Carvalho classChelsea manager Jose Mourinho believed Ricardo Carvalho should have been
awarded the man of the match award after his side drew 1-1 with Manchester
United at Old Trafford.
Louis Saha's first-half opener for the Barclays Premiership leaders was
cancelled out when Carvalho rifled a header past Edwin Van der Sar in the 69th
minute for the reigning champions.
After being told the award had actually gone to Michael Carrick, Mourinho told
Sky Sports: 'I don't believe it.
'Ricardo Carvalho was the man of the match and I want to dedicate the result
to the medical department.
'They did an unbelievable job to get him fit for this match and sometimes
people don't remember these people at the club.'
The Blues boss was happy after a much-improved second-half performance from
his side, adding: 'I think the game was easy to comment on, Manchester United
were best in the first half, Chelsea in the second.
'For me that's obvious, We didn't play well in the first half. We couldn't
play our football.
'The second half was completely the opposite and we deserved to score our
goal.'
On referee Howard Webb, he said: 'Webb did his job well. He had a good game
and I think this is what people around the world want to see - a lot of good
players and a lot of respect.'
He argued that the result was better for his side than the league leaders.
'It is a good result because Manchester United lost a big, big chance to open
the gap to six points,' he said.
'I think they faced this game when mentally very strong. They thought it was
a big chance to open the gap but they couldn't do it.
'In the second half we showed we were here to win the game.'
Manchester United 1 - 1 Chelsea
