With the long-serving Republic of Ireland international yesterday bringing to an end 12 years of phenomenal service for the Old Trafford club, it was a chance for the new guard to lead the way this afternoon.

Alan Smith – playing in Keane’s role at the heart of a four-man midfield - opened the scoring on 37 minutes.

Ruud Van Nistelrooy’s second-half double – which included a first goal in 138 from outside the penalty area – settled matters, after Darren Ambrose had drawn Charlton level.

It was Smith’s opening goal of the season – and a first since netting for United in their 4-1 win here last May.

With the 25-year-old relishing his role, the visitors had shown their intentions from kick-off, with Van Nistelrooy supported in attack by a marauding Wayne Rooney.

United, though, had to be patient to set themselves up for what would be a second Barclays Premiership win in succession.

An early ball over Talal El Karkouri from attacking full-back John O’Shea found Rooney in space in the area, but the England striker could only send a tame strike at Stephan Andersen when cutting back in from the goal-line.

Cristiano Ronaldo then shot over from the edge of the area.

On nine minutes, a chip through from Rooney allowed Van Nistelrooy to spring the offside trap.

The Dutchman drew Andersen, and slotted the ball goalwards – only for Charlton defender Hermann Hreidarsson to produce a last-gasp saving block from under his own crossbar.

There was another warning when Darren Fletcher linked well with Rooney to fashion a chance for the England striker, whose 22-yard sidefoot effort was only just too high.

The United fans behind Edwin van der Sar’s goal could be heard chanting Keane’s name – and after the opening 20 minutes, they had seen little of concern directly in front of them.

Charlton were at least now enjoying some more possession, but lacked direction and too often the ball was given away or the wrong pass selection made when in promising positions.

With 30 minutes gone, United midfielder Smith was fortunate not to be cautioned after tugging back Radostin Kishishev.

El Karkouri stuck the 30-yard free-kick well, which was blocked on the edge of the box, only for the ball to fall to Darren Bent lurking in the area.

However, the England squad man – with nine goals so far – somehow contrived to stab a shot wide of the left-hand post from six yards.

It proved a costly miss, as United took the lead on 37 minutes.

Rooney stole possession on the right, and dashed into the penalty box.

His cut-back seemed to have gone behind everyone, but Fletcher scrambled to his feet and was first to the loose ball before slotting it out to the advancing Smith to drill home a low shot from 20 yards.

Charlton started the second half brightly.

United failed to clear the danger from a corner on 50 minutes, and Van der Sar had to stand tall to deflect Dennis Rommedahl’s point-blank, angled drive over the bar as the ball was fired back into the penalty box.

United remained a threat on the counter attack down both flanks.

Rooney skipped his way through a barrage of bodies on the edge of the area, before firing a low strike just wide of Andersen’s right-hand post.

Then out of nothing, Charlton were level on 65 minutes.

Bent knocked the ball up field back into the path of Ambrose, advancing down the left.

The midfielder moved towards the centre, before trying his luck with a solid strike from 25 yards. This time, fortune smiled on Charlton as the ball ricocheted up off the back of Rio Ferdinand and flew past Van der Sar into the top right corner.

United immediately upped the tempo, and were soon back in front after 70 minutes.

Rooney picked the ball up in his own half, and charged forwards, holding off the challenges of four red shirts.

The England striker powered his way into the left side of the box, before chipping the ball over to the centre.

Van Nistelrooy collected it expertly on his chest, spun marker Chris Powell and fired into the net for an 11th goal of the season.

The Dutchman jumped the advertised hoardings and was mobbed by the United fans - earning himself a caution.

Charlton sent on Jay Bothroyd as a second striker, before Ambrose’s close-range header was straight at Van der Sar.

Van Nistelrooy then settled matters when he held off Luke Young to drive a 20-yard effort under the diving Andersen with five minutes left – and consigned Charlton to a third straight defeat after a promising start.