Preview and weather forecast courtesy of the Beeb.
Squad summary:
Charlton are without Hermann Hreidarsson, who is out for the rest of the season, but Paul Konchesky is now available again after suspension.
Alan Curbishley must decide whether to use Francis Jeffers as a lone striker or to switch to 4-4-2 to utilise Kevin Lisbie or Jonatan Johansson.
Manchester United will be without striker Ruud van Nistelrooy, who injured an ankle in training last week.
Gary Neville is still suspended but Paul Scholes returns from a ban.
United (from): Howard, Carroll, P Neville, Ferdinand, Silvestre, Brown, O'Shea, Fortune, Ronaldo, Scholes, Keane, Giggs, Miller, Kleberson, Fletcher, Rooney, Smith, Bellion, Spector, Eagles, Pique, Rossi.
Charlton (from): Kiely, Young, El Karkouri, Fortune, Konchesky, Kishishev, Holland, Murphy, Hughes, Rommedahl, Johansson, Jeffers, Andersen, Perry, Euell, Lisbie, Thomas, Fish, Fuller.
Fergie:
"Alan Curbishley is Charlton. He has resurrected that club and the disappointment for him must be that each year you think they are certain to get to the UEFA Cup but it just doesn't quite go for them. They seem to hit great runs then have little pockets of bad results and I am sure Alan is aware of that which is why he will make it tough for us today.
"Charlton are Charlton, the miracle club of the Premiership. The atmosphere there is fantastic and I love it, because it's a great ground which gets you thinking back to the days when they had 80,000 watching them. Fans packed on to that big bank opposite the main stand, and players like Sam Bartram, John Hewie and Eddie Firmani.
"I remember going down there for a youth team game 10 years ago when The Valley was a shell. The dressing rooms were portable cabins but they gave us the most fantastic buffet you have ever seen in your life. They were proud of their team getting to the semi-final of the Youth Cup and put on this amazing feast for all the directors and guests."
Curbishley:
"We now have a new kid on the block (Mourinho) and Arsene has been around some time - but the other boys have still got a lot to do to catch him up in terms of what he has achieved.
"I think for me, when you look at his record, it is not just the trophies he has won.
"When he went into Old Trafford, the stadium was not the one which they have got now, certainly the training ground is not the same, he has bought world-class players through his academy.
"So I think when you look overall at what a manager does at a football club, I don't think there are too many that can better Alex Ferguson's record.
"It is a massive game for the club, because this is what we have strived to do over the past 10 years is to play the likes of Manchester United.
"Obviously we are going into it on the run of some bad results, perhaps not with the confidence we perhaps could have, but we should still be looking forward to it because it is a big game. That is what it is all about.
"It has been a little bit torturous the last six games. This year is leaving a bad taste.
"We have had this slump and it is 'same old Charlton'. All this about switching off and losing our focus is nonsense.
"We are working as hard as we have done all season. No-one has switched off and it is ridiculous to suggest that."
Rio:
"You want to be fighting for silverware at the top of the league.
"We've not managed that this season but you can't be at a club like this and not have the motivation to play in front of 67,000 fans every week.
"If that doesn't motivate you I don't know what will."
Weather:
Sunny and 24 degrees.