Bosnia's World Cup qualifier against Turkey on Wednesday will be the toughest challenge faced by coach Miroslav Blazevic.
"I can't say I've ever had a more serious task," the 74-year-old, who has had a long and successful career, told reporters as his team prepared to face their Group Five rivals.
"This is a historic match and we must take the chance tomorrow to secure a place in the playoffs," added Blazevic who led his native Croatia to third place at the 1998 World Cup.
Victory over Turkey would secure second place in the group behind runaway leaders Spain for a team bidding to reach a major finals for the first time as an independent nation.
Bosnia, who won 2-0 in Armenia on Saturday, have a four-point lead over Turkey with three games left.
The eight best runners-up in the nine European groups go into two-legged playoffs for places at next year's World Cup finals in South Africa.
Blazevic said he was encouraged by the return of Vfl Wolfsburg's Zvjezdan Misimovic after the midfielder missed the Armenia qualifier through suspension.
"Our defensive line was lacking but now with Misimovic back in the game it is our trump card," he said.
Tickets for the match at the 25,000-seater Bilino Polje stadium in Zenica were sold out in just a few hours.