Sir Alex Ferguson's men could have been ahead before the first minute was through. Stephan Andersen, replacing the previously ever-present Dean Kiely in the Charlton goal, faltered as Wayne Rooney surged onto a throughball and watched as Darren Fletcher, charging into the area in support, glanced the young striker's cross inches wide of the far post.
A let-off, and one not punished when, three minutes later, Francis Jeffers brought down a deep cross from Radostin Kishishev, turned Rio Ferdinand, and watched as Roy Carroll pulled off a fine reflex save to turn his stinging drive aside.
In an opening spell of half-chances and snatched strikes, it was Andersen who redeemed himself, thrusting out an arm to parry Alan Smith's six-yard drive over the bar and to safety.
If Andersen was being afforded the chance to show Alan Curbishley what he could do, after an uncertain start, his audition was beginning to look very promising indeed.
A decisive stop minutes later, denying Paul Scholes when a United opener seemed inevitable added further to his standing, only for it all to suddenly unravel in dramatic circumstances.
From a deep United corner, Rooney had time to control the ball on the edge of the Charlton area, before firing a fierce drive which Andersen inexplicably spilled. Scholes hesitated not a second, jabbing the ball into the net from a couple of yards out, as Andersen reflected on a suddenly and dramatically blotted copybook.
Having shown the good side of his game with the goal, Scholes' afternoon should have ended five minutes later, as he launched a crude lunge at Dennis Rommedahl. Surrounded instantly by a hoard of United shirts, referee Dermot Gallagher handed out an absurdly lenient yellow card, rather than red the challenge deserved.
With Charlton's confidence suddenly shattered, the last thing they needed was to concede another before the break, which was precisely what they did.
In the shadow of the interval, Scholes pulled back a ball from the edge of the area and Fletcher took advantage of space and time he should never have been allowed and side-footed home from 18 yards.
As a contest, the game seemed over.
Within 17 minutes of the second half, it was. Talal El Karkouri hesitated for an age before making a half-hearted attempt to challenge for a bouncing ball on the halfway line, losing possession to Alan Smith, who strode on before depositing the ball past Andersen and into the Charlton net.
Five minutes later, a passing movement saw the Charlton defence open up invitingly in front of Rooney, who surged forward before lofting the ball neatly over Andersen.
"When you play the top sides you need for it all to go your way, and then to play at the top of your game. That didn't happen, did it? We weren't in it at any stage," said a visibly deflated Curbishley afterwards.
Chris Perry's dismissal five minutes from time for wrestling Wes Brown to the ground summed up a dismal afternoon for the home side who, long before the end, seemed desperate to hear the final whistle.
For Charlton, an afternoon to forget. For United, evidence that the race for second place in the Premiership is far from over.
"We'll keep battling away," said Ferguson. "There's great character in this side, we've shown that before, and we won't give up second place without a fight.
"That performance should send out a few alarm bells."