Sir Alex Ferguson could be forced to watch from the stands as Manchester United pursue the Premier League title as the FA considers punishing the manager for his criticism of referee Martin Atkinson.
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Ferguson was scathing in his appraisal of Atkinson's performance in United's 2-1 loss to Chelsea on Tuesday and he also said he "feared the worst" when the official was appointed to the match and implied Atkinson is not a "strong" or "fair" referee.
Managers disagreeing with controversial decisions is tolerated to some extent but the fact Ferguson questioned Atkinson's ability to handle the match could see him handed a two-match ban. Ferguson already has a suspended two-match sentence hanging over his head from his 2009 comments claiming Alan Wiley was not fit enough to referee, meaning he could face four or more matches away from the sideline if he is found guilty for this latest indescretion.
The FA has asked to see footage of Ferguson's post-match interviews to determine exactly what the manager said and in what context. It is understood Ferguson, even if found guilty, should be free to take his place in the dugout at Anfield on Sunday as United try to bounce back from the Chelsea defeat at Liverpool. Any ban would come into effect after that although an appeal by United would likely play out next week. The first match Ferguson might miss is the FA Cup quarter-final against title rivals Arsenal.
Ferguson said after the Stamford Bridge match: "You hope you get a strong referee in games like this. It was a major game for both clubs. You want a fair referee - or a strong referee, anyway - and we didn't get that. I don't know why he has got the game. I must say, when I saw who the referee was I did fear it. I feared the worst."
Ferguson argued that Atkinson should have given Chelsea defender David Luiz a second yellow card for off-the-ball fouls on Wayne Rooney and Javier Hernandez and that the penalty awarded when United defender Chris Smalling impeded Yuri Zhirkov should not have been given.
But it is the use of the word "fair" and Ferguson's implication that he had pre-judged Atkinson's ability before the match had taken place that have put the Scot in hot water.
Alan Leighton, from referees' union Prospect, said: "The idea you can have referees who are biased towards one side or another, at any level, is one that causes great damage to the game. Referees will make mistakes but they make them because they are human beings.
''It is absolutely fair for managers to say referees make mistakes. If any referee couldn't accept that they wouldn't have got past park football. But where the dividing line between legitimate and illegitimate criticism comes is when you start to question the integrity of the officials or say they are not fit to do their job, either physically or because they are biased.
''By saying they didn't have a fair referee, Sir Alex Ferguson is saying that Martin Atkinson was favouring one team or another. If you start to let those comments go, it is not far beyond for other managers to think they can also query the fairness of referees.
''If Sir Alex didn't mean that it would be very simple for him to say so and it would clear the issue up. The sensible thing to move this on would be an apology.
''I had a number of emails from Manchester United fans the last time I dared to say anything that might have been seen to be offending Sir Alex Ferguson. They said I'd been forthright and was trying to jump on the bandwagon.
''But I have just reacted to questions that have been put to us as a trade union. We are not going out trying to find issues to comment on to get media publicity.''
Ferguson will find out by 4pm on Friday if he is to be charged with improper conduct by the FA.