With such difficult games to come, our midfielder is fully aware of how crucial it is to get off to a winning start on Sunday.
"The first game is always difficult. There is a lot of tension, everyone wants to win and play well," Luka told Spurs TV Online before departing for the tournament.
"Whoever wins that game has a massive chance to go through. I hope we can win it. Ireland will be tough.
"We played against them last August and it was 0-0 and you could see at that time how hard it would be to beat them and break them down. They are very experienced, with an experienced coach.
"They have some very good players. It will be hard. Ireland are a nation, they like to fight, they have a strong, positive mentality. That’s why it will be hard for us but we have to win the game if we want to have a chance of going through."
Croatia were drawn in what can be described as a 'group of death', with fixtures against Italy and reigning world and European champions Spain to follow the match against Giovanni Trapattoni's Ireland.