The Football Association have revealed they will look into the comments made by Sir Alex Ferguson and Sam Allardyce over the weekend.
The Red Devils boss was unhappy with the fitness of referee Alan Wiley after he declared that the official could not keep up with the pace of the game, missing crucial decisions as a result.
Ferguson could also be pulled up for his touchline behaviour after he was seen ranting at fourth official Mike Dean in the second-half after a number of contentious decisions.
Many have suggested that the Scot was merely trying to deflect the attention away from what had been a poor performance by his side.
The champions needed an injury-time own goal from Anton Ferdinand to snatch a point against Sunderland at Old Trafford on Saturday.
The 2-2 draw meant that United surrendered top spot to Chelsea after the Blues overcame Liverpool at Stamford Bridge 24 hours later.
Meanwhile, Allardyce was scathing in his assessment of Peter Walton's performance after he failed to award his side what appeared to be a blatant penalty in their 6-2 defeat to Arsenal at Emirates Stadium on Sunday.
With the scores at 3-2 Walton missed Thomas Vermaelen's trip on David Dunn in the area to leave Allardyce fuming.
After the game the Rovers boss said: "We can't do anything about it unfortunately, but I've got to say publicly, to everybody, and particularly to the bosses of the referees, you've got to stop it. You must. You can't let this go on."