Bosnia will attack like a pack of hungry wolves when they rejoin battle with Portugal in the second leg of their World Cup playoff in Zenica on Wednesday, coach Miroslav Blazevic has promised.

The Bosnians, beaten 1-0 in the first leg in Lisbon on Saturday, will be without three key players through suspension but Blazevic is confident a thunderous atmosphere, and the ferocity of his players, can see them pull off a huge upset.

"We will launch an onslaught like hungry wolves from the start and I am certain that Portugal will be stunned by the atmosphere," Blazevic said.

"What we need is not support but a thunderous roar from the terraces that would put all the pressure in the world on the Portuguese," he said ahead of a match which will decide which team goes through to the World Cup in South Africa next year.

If the Bosnians do spring a surprize against the World Cup semifinalists from 2006 it will be the first time they have reached a major tournament as an independent nation.

Defenders Emir Spahic and Samir Muratovic and defensive midfielder Elvir Rahimic will miss the return leg after they were booked in Lisbon, meaning Blazevic will have to reshuffle his starting lineup.

Boris Pandza is set to replace Spahic while Zlatan Bajramovic and Miralem Pjanic should fill midfield slots in a more adventurous 3-5-2 formation with Edin Dzeko and Vedad Ibisevic up front.

Defender Bruno Alves, the scorer of Portugal's winner on Saturday, is nursing a sprained ankle and playmaker Deco has a groin strain but both are likely to be fit for a stern test in the cauldron of the Bilino Polje stadium.

Knowing an away goal would put his side in the driving seat to qualify, Portugal coach Carlos Queiroz said he would order his team to attack at every available opportunity.

"They (Bosnia) will open up more and we are going there to score, we've got to have that idea," he said.

"It will be a game of great emotions, the devil will be behind the door in every chance as risk and errors will walk hand-in-hand.

"We have to hold the ball more and control the game and be cold as we impose our own rhythm and intensity."