PREVIEW-Soccer-Portugal eye World Cup comeback without Ronaldo

* Portugal's Ronaldo sidelined with ankle injury

* Portugal coach Queiroz talks up Bosnia attack

By Shrikesh Laxmidas

LISBON, Nov 12 (Reuters) - Portugal will miss the injured Cristiano Ronaldo for their World Cup playoff but are still favourites to beat an attack-minded Bosnia side and complete a late surge to reach next year's finals in South Africa.

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.