Veteran defender Jorge Costa will sit out FC Porto's opening Group H fixture away to Rangers FC after straining his right knee in training.
The 33-year-old defender could be out for up to two weeks after suffering the injury. He has yet to play first-team football this season after being omitted from new coach Co Adriaanse's starting lineup.
Adriaanse may also be without midfielder Raúl Meireles for the trip to Scotland as the Portuguese Under-21 international sustained a blow to his right knee during Porto's league win against CF Estrela da Amadora on 21 August. Bosingwa is already sidelined with a knee complaint while new boy Marek Čech may not be risked so soon after joining the club.