Porto defender Bruno Alves scored the only goal of the game after 31 minutes when he headed in a cross from Nani.

Carlos Queiroz's side were unable, however, to score a second goal to give them some breathing space ahead of Wednesday's second leg in Zenica and could have even conceded an equaliser in the closing minutes.

With a minute remaining striker Edin Dzeko headed against the crossbar with substitute Zlatan Muslimovic also rattling the woodwork from the rebound.

"In the end we had some luck but even this advantage is not decisive. The important thing was not conceding," Deco said after the game.

"It was a difficult game, but overall we were better and controlled almost the whole game.

"In Zenica if we score a goal there, everything will be easier, but we must be very intelligent and we must hold on to the ball."

The Chelsea midfielder was substituted after 84 minutes after sustaining a knock, but believes he will be fit for the second leg.

"I felt a pain in the adductor and I came off to put ice on it, that was all it was," he added.

Portugal were without star winger Cristiano Ronaldo due to an ankle injury and in his absence they struggled to break down a disciplined Bosnia-Herzegovina side.

Queiroz admitted his side needed to improve their creative play for the second leg, but believes they are in the box seat to qualify for next summer's finals in South Africa after keeping a clean sheet.

"The important thing was to win without conceding a goal and that's what we did," he said.

"We had some opportunities to increase the advantage and to reassure the team, but we did not do it.

"Now we have to take time to relax and begin preparing for the second game. But as we saw, Bosnia has a lot of quality and we have to go there at full capacity and play with our heart and minds."