The chief executive supported the notion that the new national stadium should be used primarily to showcase football and that other events would have to fit around it.
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Aston Villa boss O'Neill was critical of the pitch following a 2-1 defeat by Manchester United in the Carling Cup final last month and, as a self-confessed traditionalist, supported Watmore's view.
'I think Wembley should be kept just for football,' he said. 'Of course, I realise in this modern day people have to make some money and there could be the occasional game to be played on it like a rugby final.
'But I wouldn't want somebody playing on it on a regular basis, weekly or fortnightly. Not if you want some showpieces on it like a Carling Cup final, or an FA Cup final or semi-final. I happen to think that should be the case, but that's clearly not how they're thinking about it.
'Maybe that's one of the reasons there's been a bit of a fallout.'
United manager Sir Alex Ferguson even blamed the 'heavy' Wembley turf for the hamstring injury suffered by striker Michael Owen in the first half of the final.
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