Sir Alex Ferguson claimed referee Martin Atkinson's decisions which led to Chelsea's winning goal at Stamford Bridge were the kind which lead managers and players to "lose faith in refereeing".

Atkinson awarded a free-kick for Darren Fletcher's challenge on Ashley Cole, and Wes Brown appeared to be impeded as Frank Lampard's delivery was turned into the net.

An unhappy Ferguson told Sky Sports 1: "Clearly, Darren Fletcher's won the ball - Ashley Cole's never touched and has jumped up in the air - and then (Didier) Drogba's pulled Brown to the ground for the goal.

"The referee's position to make the decision was absolutely ridiculous, he can't see anything. He's got a Chelsea player (Joe Cole) standing right in front of him and he doesn't even move.

"It was a bad decision, but there's nothing we can do about it. You lose faith in refereeing sometimes, that's the way the players are talking in there - it was a bad one."

Ferguson stopped short of blaming Atkinson for his side's defeat, admitting instead they should have taken the chances they created.

"That goal should never have been allowed. We've dominated the game; we've had great chances to win the match - and that's our fault," he told Sky Sports 1.

"We had great opportunities to get to the edge of the box and some really good chances in and around the box, but we should be finishing it off.

"We've only ourselves to blame in that respect. But you do need a break - and we never got the break we needed."

He admitted the defeat - United's third on the road this season - was more significant than their recent 2-0 reverse at another rival club, Liverpool.

"The fact is Chelsea go five points clear of us," he said.

"The defeat to Liverpool didn't affect our position in the league - that affects our position in the sense that if we'd have won we'd have gone top today."

Chelsea boss Carlo Ancelotti was also unhappy, with the way United players appeared to try to get one of his players sent off.

In a stormy second half, United midfielder Fletcher waved an imaginary card in an apparent attempt to get Chelsea defender Ricardo Carvalho dismissed.

Ancelotti said: "The Manchester players protested a lot. I don't know why. I don't like this. At the end of a very difficult match, all the players worked very hard - and sometimes it can happen."

Ancelotti admitted Drogba might have been offside for Chelsea's goal but said: "It was very difficult for the linesman to see. There was a lot of concentration of players in the box.

"We are in good position in the Premiership and in the Champions League. The players have done very well. We have to continue, because there will be other strong matches like today."

Captain John Terry praised Chelsea's team effort as they shut out United despite facing sustained pressure.

Terry said: "Another clean sheet for us today, we talk about the attacking players and midfielders coming back and working hard for the team and that's exactly what we got today.

"(The five-point lead) was exactly what we wanted coming into the game, we've been working on it all week. That wasn't the best of games but I think overall we deserved it."

The scorer of the goal was unclear, with both Terry and team-mate Nicolas Anelka appearing to make contact with Lampard's free-kick on its way into the net.

Terry said: "I got a touch on it but I think maybe Nico got the second touch - but I'm still claiming it!

"I was watching the stats before the game and I've never scored against them home and away, but Nico's been brilliant today so he deserves it."

Anelka added: "I don't know, I think I touched the ball but maybe John will claim it. I touched the ball but I don't know what happened after that, we will see on TV."

"We played good football and we had some chances but we stayed compact in defence and managed to score one goal.

"It's very good, we wanted to win because we know United are a big rival for the league and it's always good to have five points on top of United."

Terry played down appeals for a first-half penalty to United after his challenge on winger Antonio Valencia, telling Sky Sports 1: "I just got my body in between the ball (and Valencia), I'm glad (Atkinson) didn't give it but I didn't think it was anyway."