By Paul Fletcher Our man in Porto

Jensen leads the Danish training group in Portugal

Denmark midfielder Claus Jensen has revealed that fitness was the reason behind his team's superb performance against Italy on Monday.

"One of the things we've focused on is fitness," Jensen told BBC Sport after the 0-0 draw.

"It has been really hard - a bit like pre-season training in the run-up to the first game.

"Every one of our players looked very fit against Italy and hopefully we can take that forward."

Denmark were criticised after some poor pre-tournament displays, including a 2-2 draw with Estonia.

But Jensen put those performances down to the intense fitness work the squad was going through at the time.

And when it really mattered - in the searing heat of Estadio do Afonso Henriques in Guimaraes - Denmark looked very strong.

"Obviously Italy are always among the favourites but we were the team that started to make the game," added Jensen.

Sweden is a big game but it is not the biggest - that is Bulgaria because they are the team we play next Claus Jensen

"We tried to go and score goals and that is what we want to do as a team."

Italy were rightly criticised after a torpid display - struggling to adjust to pitch-side temperatures that reached 34 degrees.

But Jensen warned against dismissing teams who are notoriously slow starters at major tournaments.

"They showed on a few occasions they can create a chance out of nothing," the Charlton player added.

"Italy are always dangerous and you can never under-estimate a team like that."

A huge Scandinavian derby with Sweden will complete Denmark's Group C campaign.

But Bulgaria, thrashed 5-0 by Sweden, come next.

And Jensen is sure that the scoreline against the Swedes paints a false picture of the task they face.

Bulgaria created numerous chances against Sweden before capitulating towards the end.

"Sweden is a big game but it is not the biggest - that is Bulgaria because they are the team we play next," added the Danish midfielder.

"If we can get a great result from that game, there will be less pressure going into Sweden.

"We played Bulgaria in a World Cup qualifying game a couple of years ago and we know their strengths.

"I play with former Bulgarian international Radostin Kishishev at Charlton and he says they have a good young side now and have a lot of talented players."

Denmark, as with Greece on Saturday, may have surprised the casual observer, who no doubt had marked their illustrious opponents down for a straightforward win.

But after conceding eight goals without scoring at Euro 2000 and suffering a tame second-round defeat at the World Cup to England, they are determined to qualify from their group and restore pride to Danish football.