Chelsea boss Andre Villas-Boas was critical of referee Howard Webb after his side lost a three-goal lead to draw 3-3 at home with Manchester United.
Webb awarded United two penalties - both converted by Wayne Rooney - that changed the course of the game.
United's draw at Stamford Bridge helped them close the gap on Premier League leaders Manchester City to two points.
"The first one is an obvious penalty, nothing to say, but the second one is very, very dubious," said Villas-Boas.
"I don't know if Howard Webb had the correct angle to make the decision but it is very unlucky for him to give it.
"It is Danny Welbeck's leg that collides against Branislav Ivanovic's."
United boss Sir Alex Ferguson insisted that both penalties were "justified", even suggesting, with particular reference to Gary Cahill's first-half collision with Danny Wellbeck, that: "We could have had four penalties."
Villas-Boas added: "I don't know if Howard is compensating for anything from the first half but it is a wrong decision.
"To go from 3-1 to 3-2 is immense and 3-3 is almost normal service for United. They have great desire and ambition. They never give up and manage to get the result, not the completely positive one they wanted, but a draw from 3-0 is important.
"The way it happened is a big disappointment. We expect top referees in the top games and at the moment it is not happening for us.
"It didn't happen for us against Manchester United at Old Trafford with two offside goals and it didn't happen for us again here with a dubious decision that shifted the running of the game."
Chelsea looked to be on course for three points when Jonny Evans' own goal, a spectacular strike from Juan Mata and David Luiz's deflected header looked to have give them an unassailable lead.
But Rooney's two penalties gave United the momentum to earn a point courtesy of Javier Hernandez's late header.
Villas-Boas admitted his disappointment at Chelsea's failure to protect their 3-0 lead, saying: "You have to try and hold on to a lead, but it was cut short by two penalties.
"The decision to give a second penalty for a team has to be taken with a clear mind and hopefully it was taken with a clear mind by Howard.
"The disappointment from our fans is most noticeable and they are right. We wanted to give them a massive lift in terms of motivation, so it's a pity we couldn't give them that."