The visitors were still holding Sir Alex Ferguson's side after an hour of the north-west derby when Jlloyd Samuel slid in on Cristiano Ronaldo.

Most of the stadium felt Samuel's tackle had been a good one. Despite being perfectly positioned, referee Rob Styles took the opposite view.

Ronaldo scored the penalty, paving the way for a 2-0 win and an unhappy Megson.

"It was a nonsense decision," argued Megson.

"When Rob Styles blew the whistle I thought he was going to book Ronaldo for diving. He did not seem to be sure what he was going to give.

"My thoughts on the tackle were the same as everyone else's in the stadium apart from one man. When the referee sees it again, he will have the same opinion too. It really sticks in the throat."

It is not the first time Styles has attracted criticism for a debatable penalty decision, having been briefly dropped from top flight duty 12 months ago when he gave a spot kick to Chelsea against Liverpool when Steve Finnan had barely touched Florent Malouda.

"I don't want him to ring me up," added Megson.

"I would have more respect from him if he just holds his hands up and says he was wrong.

"If he tried to justify that it will be incredible.

"I don't know if we would have gone on to get something out of the game but we certainly would not have gone 4-4-2 and we would not have made changes to try and score."

Even Ferguson accepted Styles had got it wrong, although as the official has previously angered the United boss with his decision-making, he does not feel much sympathy.

"I was surprised because it looked as though their lad got a foot on the ball," said Ferguson.

"But Rob Styles turned us down four or five times last year so maybe it is payback time. But he still owes us another four."

Wayne Rooney's excellent finish 11 minutes from time doubled United's lead, the England striker's first goal of the season a perfect response to being left out of Ferguson's starting line-up.

"He made a difference when he came on," said Ferguson.

"If we are getting responses like that from players it is terrific for the club."

Ferguson confirmed Owen Hargreaves is likely to miss the Champions League encounter with Aalborg in Denmark on Tuesday with a knee injury, although Wes Brown, who also sat out today's win, is expected to play.

That is of little consequence to Megson though, having seen an hour's worth of honest endeavour get no reward.

"I want to see the right decisions made," said Megson, whose side had the best chance up to that point when Fabrice Muamba fired wide from an excellent position.

"If TV replays take too long then we won't do them but from looking at other sports, TV can do these things.

"They talk about dropping the referee but what does that solve? It is just a symbolic gesture.

"Everybody knows what happened. Jlloyd Samuel won the ball. It is astonishing."

ends