Grant McCann and Alex Bruce have withdrawn from the Northern Ireland squad for Tuesday's World Cup qualifier in Portugal, the Irish Football Association have confirmed.
Peterborough midfielder McCann has a knee problem and Hull defender Bruce a groin injury and both have returned to their clubs.
Manager Michael O'Neill has not called up any replacements at this stage.
Portugal lost 1-0 to Russia on Friday to sit second in Group F on six points from three games. Northern Ireland have one point from two matches.