TEGELEN, Netherlands, June 10 (Reuters) - Spain have made a belated acknowledgement that Norway are likely to be their biggest threat to a place in the quarter-finals at Euro 2000.

Norway are something of an unknown quantity to the Spanish, who are far more familiar with the style of the Yugoslavs.

Players such as Predrag Mijatovic, Savo Milosevic, Darko Kovacevic and Miroslav Djukic all achieved star status in Spain and Spanish preparations have in turn been based on the assumption that they, rather than the Norwegians, will be their main rivals.

The Spanish squad stayed in their hotel on Friday night to watch videos of Norway in action and they appear to be coming to the conclusion that their opening game in Rotterdam against Nils Johan Semb's side might just make or break their tournament.

'Norway are going to be the toughest side we face in the group stage,' said Pep Gaurdiola on Saturday.

'Our styles are so different, it's like night playing day.

'Their way of playing is going to cause a lot of problems for us and we'll have to be at full concentration for 90 minutes.'

Fellow midfielder Fran Gonzalez added: 'They're a hugely complicated rival for us but we do need to get those three points to help us settle.'

That view was backed up by former coach Javier Clemente, in a column written for Spanish sports daily Marca.

The man who led Spain into Euro 96 explained: 'Norway will be the hardest side for Spain.

'They have a combination of strength, technique and attacking danger.

'They have a reputation for playing high, long balls but it's not true. It's a combination of rhythm and technical quality.'