Ireland's opening match against Croatia at the European Championship already has a make-or-break feel to it.

And with Giovanni Trapattoni in their corner, the Irish know they have a coach for the big occasion.

The 73-year-old Italian has won titles in four countries and won the European Cup with Juventus. Steering Ireland out of a group containing Spain and Italy, the last two winners of the World Cup, would rank nearly as high.

''I'm not particularly excited, but I'm a little tense because I want to keep (up) the level of tension for the players,'' Trapattoni said. ''Positive tension is important.''

When it comes to preparing teams for big matches, few coaches in world football can match Trapattoni, who on Sunday will become the oldest coach in European Championship history. He was in charge of his native Italy at the 2002 World Cup and at Euro 2004.

Up against Trapattoni will be 43-year-old Slaven Bilic, who has impressed since taking the Croatia job six years ago despite having no coaching experience at club level.

Bilic, who will step down after the tournament finishes to take over at Lokomotiv Moscow, lauded the defensive strength that has allowed Ireland to go on a 14-game unbeaten run stretching back more than a year.

The two teams played out a scoreless draw in a friendly last August.

''I have big respect for the Irish team. They are very good, very impressive,'' Bilic said. ''We have a Plan A, a Plan B and a Plan C if necessary.

''With the greatest respect for the Irish, we see our chance against them, but ... we've proved in history, and they've proved in history as well, we can beat those big guns as well.''

Ireland captain Robbie Keane, who will partner Kevin Doyle in attack against Croatia, said Trapattoni's know-how gave the squad confidence it could advance from the group.

''Our manager certainly gets the best out of the players,'' Keane said. ''When you get someone like Trapattoni, he knows exactly what he has to do. He's been in the game for a long time, he has won nearly every trophy possible so he certainly knows his stuff.''

Trapattoni has made no secret of his intended starting 11 to face Croatia. Goalkeeper Shay Given has shaken off a series of niggling injuries and should start with the team that drew 0-0 draw against Hungary in the last warm-up match on Monday.

Croatia has had a more fractured build-up.

Veteran striker Ivica Olic withdrew with injury in the run-up to the tournament, while Ivo Ilicevic pulled his left calf muscle on Wednesday and has been replaced by 20-year-old midfielder Sime Vrsaljko.

Defender Vedran Corluka has been cleared to play, however, following a hamstring problem that forced him to leave training early on Thursday.

For Croatia, much will hinge on the influence of creative midfielder Luka Modric, who will try to unlock the Irish defense with his penetrating passing from deep.

''For us that very first game is very important,'' Modric said. ''If we can win that first game, we can pass through the group.''