Former Republic of Ireland captain Roy Keane believes Giovanni Trapattoni's men are capable of "one big result" at Euro 2012 - which he feels must come in their Group C opener against Croatia.

After being drawn alongside World champions Spain and powerhouses Italy, few give Ireland much chance of making an impact on the business end of the competition.

However, confidence within the camp continues to grow, and Trapattoni's squad were again well organised in their final warm-up game against Hungary, which ended in a battling goalless draw.

Keane feels if Ireland can produce the goods in Poznan on Sunday night, then they stand every chance of upsetting the odds again in their final two group matches.

"It will be tough for Ireland, but they will have a good go as all Irish teams do," said Keane.

"The biggest game for Ireland is the game against Croatia. They have to get something because if you go to the second game against Spain without a point, it will be very, very difficult."

Keane continued: "But what you might find with Ireland, which they have done in all major tournaments in which they have qualified, is that they get that one big result - but they have to get a result against Croatia."

Keane, 40, continued: "Ireland always bring something different to a tournament - they have spirit, the supporters, that gives you a chance.

"Technically they will be well behind the three teams they are playing, and they will have very little possession, but recently, you look at Chelsea, in football matches, possession has not been the biggest priority - it is about keeping solid.

"They are not bad at set-pieces, and that may be their only hope."

One player the opposition scouts will have done well to brush up on is Sunderland winger James McClean.

The 23-year-old - who was born in Derry and represented Northern Ireland at under-21 level - has enjoyed a breakthrough season in the Barclays Premier League after being fast-tracked into the first team following the arrival of new manager Martin O'Neill.

"He is a good player, and it is good for Ireland, you need young players coming through," said Keane, who had a spell in charge of the Black Cats from 2006 to 2008, taking them into the Premier League.

"Obviously he has had some difficulty because he has been criticised for not playing for Northern Ireland, but he has made his decision.

"He has enjoyed playing under Martin, has had a break there and been a good asset.

"He might be a surprise package in that the other teams won't have seen too much of him, because he is a big strong boy, and can get you goals.

"If he can bring his club form to the team he can get in that starting XI."