Alex Ferguson last night insisted he would not tolerate any criticism of players from within Old Trafford being made public. His warning served to rebuke his captain Roy Keane and justify the manager's decision to can the Irishman's infamous diatribe on the club's own television station about sliding standards at Manchester United and the team's recent slump in form.

Ferguson marks the 19th anniversary of his appointment tomorrow with the visit of the runaway leaders Chelsea, an appropriately momentous occasion on which to end one of the most turbulent weeks of his managerial career.

The Scot admitted the Londoners' financial clout had forced United to rethink the philosophy that had previously established them as the Premiership's driving force, though his principles regarding the airing of frustrations felt at the club remain unchanged.

"Criticism's expected and comes from all sides but, as the manager of Manchester United, I won't be criticising anyone at this club," he said. "My stance remains unchanged, unequivocal, unremitting. You have to make sure the criticism remains in-house so anything we do at this club will remain indoors. I think that's the example United set from their manager down, and I think that's really important. I won't change and neither will the club."

That Ferguson went out of his way not to mention Keane as he effectively went about publicly criticising his captain for publicly rebuking other players merely added to the sense of farce that has enveloped United this week. After a stuttering start their season has threatened to disintegrate entirely with damaging defeats by Middlesbrough in the Premiership and Lille in the Champions League. Keane's explosive comments and the executive decision not to air them added to the turmoil.

Given the circumstances, Chelsea's arrival tomorrow - when they will attempt to extend a 40-match unbeaten league run and stretch their lead over United to 16 points, probably with representatives of the Glazer family present - hardly appears ideal. Ferguson preferred to be bullish, insisting he had faith in his players' ability to beat Jose Mourinho's leaders. Just as he set so much store by United ending Arsenal's 49-match unbeaten run last season, he recognised this as the opportunity for his side to demonstrate Chelsea are far from invincible.

"It's the one chance we've got to say to the rest, look, maybe we can beat Chelsea," he said. "It's always a challenge but there's also a duty for us to be up there all the time at this club.

"Chelsea's consistency has probably been better than ours way back in the '90s . . . but what they've done has brought changes on us as to how we view our own development, in particular how we bring players in from other clubs. If we're doing something (in the transfer market) we have to be really quick and decisive before Chelsea find out about it. I know that they're quite happy to buy somebody just to keep them away from Arsenal and United. They can do that because they've got that much money.

"I wouldn't say I'm jealous. I wouldn't mind that kind of money myself, but managing this club is different anyway. I probably wouldn't use that money, if I had it, as much as they do because I think it's important to still have a healthy youth system, and I think we have that. There is a lack of confidence, but I'm having to play my young players. They've done very well. They've been through the mill, tried their best and I've no complaints.

"We know this is a big game but, Christ, we've had some big games in the past. It's not the biggest game we've ever had. I know my players have the ability to do something on Sunday. I'm going to rely on that and trust them."

Even so, the sight of Michael Essien - a player Ferguson scouted extensively last season - trotting out in blue alongside the previous United targets Arjen Robben and Damien Duff will rankle, despite his admiration for Mourinho.

The Portuguese had declared his opposite number "number one" in terms of prestige, status, silverware and years at a club, and added: "He doesn't need support or sympathy; he just needs people to respect what he's achieved."

"I like him," responded Ferguson. "Okay, there are other parts surrounding his club which concern me, and I think everyone else in the world, but his management's been good for the game . . . He's got his opinions. Some I agree with, some I don't, but I don't think it's done Chelsea any harm because it's given them a profile they've never had before. I find his 'observations' quite amusing.

He's also a manager who'll come in for a drink after a game no matter what the result . . . I suppose there are parallels with him coming in and me coming in at Aberdeen (where Ferguson broke the Old Firm duopoly). I remember my first game with Aberdeen at Ibrox and we drew 1-1. They were all dancing in the dressingroom but I was raging. They were thinking it was the best result they'd had in their lives. I had to change that."

Ferguson did. Whether he can again, faced by Mourinho's dominant Chelsea, remains to be seen.