Key Croatian defender Vedran Corluka has tipped his side to emerge from Group C after being cleared to play against Ireland in Poznan tomorrow night after doctors examined his hamstring complaint.
"I know that if we don't go to the next stage, it will not be a success, but of course, you never know," said Corluka, who was given the all clear after travelling to Warsaw.
"Like in Euro 2008 you were thinking it was a success to go to the next stage, but then we lost against Turkey in the quarter-finals and we were thinking that wasn't a success.
"We'll see. If you get a good team in the next stage it can be really difficult, but the first goal is to qualify."
Manager Slaven Bilic could decide to deploy Corluka at full-back, where he links well with former Spurs team-mate Luka Modric, the side's key playmaker, or in the occasionally vulnerable centre of defence, despite concerns about the 26-year-old's lack of pace.
"They've done a scan this morning and it showed, thank God, nothing, no rupture... so we are expecting him to play on Sunday,'' said a delighted Bilic.
"It is a relief as Corluka is one of our generals, like a senator, and he's the leader of the defence and he's one of the most important players for us.''
Bilic denied that the Ireland game was pivotal for his team's qualification chances in a group where Spain and Italy are favourites to qualify, but acknowledged that it represents Croatia's best opportunity for making progress in the tournament.
"Nothing will be decided after the first game. We can come closer to pass the group stage or make our chances less, but still everything is going to be open after the game.
"We've proved in history, and they've proved in history as well, we can beat the big guns as well.''