On the Premiership: Manchester United roared their defiance yesterday. A bad week, pockmarked by two crushing defeats, a torrent of venomous criticism from the club captain Roy Keane and the media storm which inevitably followed, ended with Alex Ferguson's chastened team bringing Chelsea's year-long unbeaten run in the Premiership to a shuddering halt.

Too little, too late, perhaps. United still trail Jose Mourinho's side by an eye-watering 10 points, and there is little to suggest the Londoners are on the verge of implosion. But a performance that bristled with attacking intent in the first half and defensive resilience in the second has restored United's credibility just when they seemed to have lost it for good.

We can only wonder what Keane made of it all. The skipper had suggested in an interview with MUTV, the club's official television station, that United, once the antithesis of mediocrity, are now cultivating it. The programme was canned after consultation with Ferguson, but not before it was revealed that Keane had singled out five players - Darren Fletcher, Alan Smith, John O'Shea, Rio Ferdinand and Kieran Richardson - for especially virulent condemnation.

This is not the first time that Keane has flagrantly flouted Ferguson's golden rule that all criticism must be kept in-house. Just last month he took a swipe at the club hierarchy by claiming that they had been tardy in offering him a new contract. But while his previous outbursts have been excused, if not encouraged, by the management, the deeply personal nature of his latest remarks mean that there is perhaps no way back for the United skipper.

Keane's assessment of Fletcher - "I can't understand why so many people rave about him" - was particularly spiteful. The Scot is a bit-part player, hastily promoted to the status of first-team regular because of United's injury crisis, and did not deserve such public humiliation.

His reaction to the comments - an exquisitely-judged looping header that sealed United's win yesterday - suggested he is made of sterner stuff than Keane might have imagined.

Smith, too, has a right to feel aggrieved. Ferguson has developed a bizarre theory about his £7million purchase from Leeds, one which explains the striker's poor goals-to-games ratio by insisting he is actually a defensive midfielder in disguise. So when Keane suggested that Smith spends his time "wandering around as if he is lost" the Yorkshireman probably just nodded in agreement.

Smith was exceptional against Frank Lampard yesterday and his frenzied fist-pumping at the final whistle was the reaction of a vindicated man, but one fine performance cannot disguise the fact that he lacks both the technique and temperament to flourish as a central destroyer.

Keane's verbal volley should, perhaps, have been directed more at the senior pros within United's squad, who have allowed their high standards to slip this season. The ginger-haired genie Paul Scholes was a persistent menace against Chelsea, but his form over the past two seasons has not justified his decision to bring his England career to a premature end.

Another key creative force, Ryan Giggs, is also starting to show his age. The Welshman is currently injured - another sign of his advancing years - but when he does play, he has all the fizz and sparkle of a damp firework.

Then there is Rio Ferdinand. Before the start of the season, when United were attempting to persuade their England international to sign a new contract, his agent Pini Zihavi claimed that his status as "the best defender in the world" deserved appropriate remuneration. Right now, however, Ferdinand is not the best defender in his own family, let alone the planet. Little brother Anton helped West Ham to another clean sheet on Saturday, their fourth in 11 Premiership games this season, and it is safe to assume he will not now demand £120,000-a-week from Alan Pardew.

Ferdinand is an easy target. Supersized wages demand superhero performances, but the centre half is far from that.

Just like lesser beings, he needs confidence, but that has been drained by his own poor performances and the media attention that has inevitably followed. Perhaps his commanding display yesterday will allow the swagger to return.

The Premiership needs a strong United. The buzz which enveloped Old Trafford as Chelsea were harried and harassed out of their rhythm in the Manchester murk was shared by the rest of the top flight, which thrilled at the sight of the league leaders being made to look so fallible.

Now the challenge for Ferguson's team is to prove that this was not a one-off. The omens are good. Gary Neville - one of United's genuine world-class performers - is set to return to his right-back berth after the two-week international break, while Keane's comeback from injury is also imminent.

On yesterday's showing, Smith, Fletcher and co may just keep their captain on the sidelines. Keane's reaction to that would be worth hearing.