A scan today of Denis Irwin's injured knee is expected to confirm that ligaments were damaged in a horrendous tackle by Paul Bosvelt during Manchester United's 3-1 win over Feyenoord in Rotterdam on Wednesday.

A minimum of six weeks is being put on his recuperation, although a club spokesman said yesterday that depending on the result of the examination, it could be longer.

It means that the player will miss the return World Cup meeting with Belgium in Brussels in eight days time, a serious setback for Mick McCarthy at a time when he needs all the experience he can muster.

Initial fears that Irwin's leg had been broken were not substantiated and instead of having to go to hospital in Rotterdam, he was able to return to his home in Manchester immediately after the game.

At his home yesterday, he spoke of the injury which was originally interpreted as a career-threatening one. "You don't expect to be hit with tackles like that, in the situation I was in, and my initial reaction was one of shock.

"I knew the tackle was a bad one but I didn't realise how bad until I watched it on television when I got home. It looked awful. A couple of minutes earlier, a Feyenoord player, possibly the same one, had narrowly missed me with another high tackle, out near the touchline. But I still wasn't prepared for what followed.

"If there was a silver lining, it was that I had my leg off the ground at the moment of impact. If I hadn't, I shudder to think what might have happened. Even before I got hurt, I wasn't happy with the standard of refereeing - and neither were the other players.

"The difference in the attitude of the Feyenoord players after they came back on to the pitch in the second half was amazing. In the first half, they barely raised a gallop but whatever was said to them during the half-time break, they were all fired up when they returned."

"I'm naturally disappointed that I'm not going to be involved with Ireland in Brussels next week, It's a huge game to have to miss, but hopefully we're still going to get the result which will take us to the World Cup finals."

Alex Ferguson, who became embroiled in a war of words with the Feyenoord coach Geert Meijer as Irwin lay injured on the pitch, could now face disciplinary action by FIFA for his post-match outburst.

Ferguson, outraged when Meijer appeared to spit chewing gum in his direction, was seen to be upset by the referee's inertia as much as the unrepentant attitude of the Dutch bench for Bosvelt's tackle.

Confirming that Irwin would be out for some time, he said: "I'm sorry that he's going to miss an important World Cup game for Ireland for I know how badly he wanted to play in it. I'm also sorry that he's not going to be available to Manchester United for an important part of our domestic and European programme.

"In retrospect, it can be said that he is a very lucky lad for he could so easily have come out of the game with a broken leg. It was as bad as that.

"I'm particularly sad that it should happen to a player like him. Denis is not the physical type - he is a gentleman defender who has been booked, perhaps no more than five times in six years of tough competition."

Mick McCarthy who attended Newcastle United's European game against PSV Eindhoven at St James' Park on Wednesday, specifically to check on Eindhoven's two Belgian strikers, Luc Nilis and Gilles De Bilde, did not see the Irwin incident until he watched edited highights of the game.

"Frankly, I'm not surprised Alex Ferguson got upset," he said. "It was an appalling tackle on Denis - tackles like that are unacceptable in the modern game.

"I've not yet had a chance of speaking with the player but unfortunately, it can be taken as read that he will not play in Brussels. That, certainly, is a bad blow for players of his experience are difficult to replace. But we shall give it our best shot."

McCarthy declined to speculate on the likely replacement at left back until such time as Irwin's injury has been identified precisely but clearly, the transfer of Steve Staunton to his old role is one option.

It was confirmed yesterday that a team of Austrian officials will take charge of the game in Brussels. It will be refereed by Gunter Benko with Manfred Zeiser and Egon Bereuter acting as his assistants.