Sir Alex Ferguson slammed the match officials as Chelsea leapfrogged Manchester United at the top of the table with a 2-1 win at Old Trafford.
Didier Drogba scored a contentious second goal for Chelsea after Joe Cole had given the visitors a first-half lead.
Drogba appeared to be in an offside position as he collected Salomon Kalou's pass before smashing the ball past Edwin van der Sar.
Ferguson was left fuming that the goal was allowed to stand as Federico Macheda's late effort proved to be a mere consolation for the home side.
"What I can't understand is the linesman's directly in front of it," Ferguson told Sky Sports 1. "He has no-one near him and he gets it wrong.
"A game of that magnitude, you really need quality officials and we didn't get them today. It was a poor, poor performance."
Referee Mike Dean has been in the spotlight this week after Blackburn's Martin Olsson admitted he deliberately went down in the area at Burnley because of Dean's reputation for giving penalties.
United had two penalty appeals turned down at Old Trafford while Chelsea also looked to have a good shout when Gary Neville barged Nicolas Anelka.
Asked whether Dean had been affected by the comments, Ferguson added: "I don't know about that but when I saw Mike Dean I did worry, I must admit."
FavouritesThe win moves Chelsea two points clear of United with five games to go, and Ferguson believes Carlo Ancelotti's men are favourites for the title.
"Five games left, they're two points ahead and four goals better than us - they're in the driving seat," continued Ferguson.
"Chelsea are favourites now, there's no question. I'm certain we'll respond but we could win the next five games and not win it."
Will Chelsea's win at Old Trafford prove the decisive moment in the title race?