Manchester United boss Alex Ferguson insisted referee Graham Barber was wrong to impose midfielder Nicky Butt's second red card in five days in the 3-0 hammering at Highbury.

But the Old Trafford chief admitted there could be no excuses for his side's comprehensive defeat.

Ferguson said: "I thought that Arsenal had far more determination to win a game of football than we did. They earned the right to win the match by sheer effort and determination.

"We were second best in every challenge, particularly in first 20 minutes and it was a really disappointing performance.

"Some days you can find no excuses and this was one of them. Arsenal were the worthy winners - no question about it."

Asked if the sending-off of Butt for a foul on Arsenal's Patrick Vieira in the 51st minute was critical to the result, Ferguson offered an emphatic "No."

"It was always an going to be an uphill battle well before that," he said. "But the decision was wrong. People are talking about having full-time professional referees but how can that improve a decision like that?

"You can either make the decision or not and unfortunately for Nicky Butt it was a bad decision.

"But that doesn't alter the fact that Arsenal were far better than us and I don't like saying that as a Manchester United manager.

"As a group of players we have ascended to great heights over the years and hopefully a display like this today won't be repeated," he said yesterday.

Arsenal manager Arsene Wenger had sympathy for Butt. He said: "It was a 50-50 sending off. Some times in those situations you see a yellow card and some other times you see a red one.

"Patrick Vieira was on top and looked as if he could have scored before he was fouled, but maybe there was still a chance for another defender to get back and tackle him.

"I don't think it made any difference to the result. We were back to our best again and it was a continuation from the way we played in the second half against Lens on Wednesday."

Wenger was delighted with midfield star Vieira's magnificent display. "I don't know if it was his best performance for us, but certainly in the top three.

"He was outstanding and the whole team played well. We badly needed a win because we have had five draws in the last five games and that is too much.

"If we had not won today it would have been very difficult to make up the ground.

"We have not been scoring enough goals, but I just told the players that so long as they kept improving our game the goals would come."

"We can go on strongly from here, but we need the same level in games against teams who do not have as much prestige as United. It must be our aim to keep up this standard in every game."

Meanwhile at Ibrox, where Lionel Charbonnier made two exceptional saves yesterday to deny Celtic victory in the first Old Firm derby of the season, the French star played down his role in a game that the Ibrox side dominated. "It is not important how I perform. It is how the team plays that counts. I was happy to be in the right place when Larsson got the ball. It was a very powerful header," he said.

"I saw the shot from McKinlay very late but got a touch to it. But that's my job."

Rangers coach Dick Advocaat was furious at the way his side had passed up the chance to go clear of their rivals.

"We played very well in the first 85 minutes and created so many chances.

"At this level you have to convert some of them and it was very disappointing for me that we didn't."

Celtic coach Jozef Venglos expressed his delight at the end of a difficult week, which saw a number of players receiving treatment.

"It was a good derby and a very exciting game," he said. "The players showed determination and worked hard for each other. I enjoyed my first derby. It was very competitive but played in the spirit of friendship."