Portugal confident despite Ronaldo setback
The uncertainty over the Real Madrid player's ankle injury was settled when tests ruled him out of Saturday's game in Lisbon and the away leg in Zenica four days later, but it has overshadowed the run-up to an intriguing encounter.
Portugal's resurgent side are 10th in the world rankings, 32 spots above their opponents, but Bosnia are a free-scoring team close to their first major finals.
"In theory, we have an obligation to win. We are a serious candidate to be at the World Cup," Portugal coach Carlos Queiroz said.
Portugal have momentum after winning their last three qualifiers to recover from three draws that took them off course.
The Portuguese defence was among the tightest in the qualifiers, letting in only five goals. Right-back Jose Bosingwa is injured but in Paulo Ferreira and Miguel they have suitable replacements.
Their backline will, however, be tested by a strong Bosnia attack that scored 25 goals in 10 qualifiers.
"They have three players that can create goals on their own," Queiroz said.
He singled out striker Edin Dzeko, who scored nine goals in qualifying and helped Wolfsburg win the Bundesliga by netting 26 times last season.
Dzeko's club-mate Zvejzdan Misimovic is a classy number 10 and Zlatan Muslimovic is also a prolific scorer, while Lyon's Miralem Pjanic is deadly from free kicks.
Coach Miroslav Blazevic, the wily 74-year old who took Croatia to the 1998 World Cup semi-finals, said Bosnia would try to stifle Portugal in midfield and could not afford to sit back.
Bosnia's defence conceded 13 goals in the qualifiers and will be relieved not to face Ronaldo, although Portugal are dangerous even without him.
Nani and Simao both played well and scored in Portugal's qualifying revival, while Liedson is a dangerous poacher.
Queiroz hoped playmaker Deco could replicate his recent form for Chelsea. The coach was also confident the Portuguese players' experience would be a key factor.
"We have to use our experience and maturity. This game may seem like it is the game of our lives. It would be important if our players found the tranquillity to face it as just another game in their careers," Queiroz said.
Portugal: Eduardo; Miguel, Ricardo Carvalho, Bruno Alves, Duda; Pepe, Deco, Raul Meireles; Nani, Simao Sabrosa, Liedson.
Bosnia: Kenan Hasagic; Emir Spahic, Sanel Jahic, Boris Pandza, Safet Nadarevic; Elvir Rahimic, Zvjezdan Misimovic, Sejad Salihovic, Miralem Pjanic; Edin Dzeko, Vedad Ibisevic.
Referee: Martin Atkinson (England)