The defender could face a spell on the sidelines with a knock sustained while on international duty, as his disappointing start to the season continues
The defender featured from the start in the Seleccao's defeat, but was forced to leave the pitch after only 20 minutes as a result of his problem.
It is not yet known exactly how long Coentrao will be out of action, with the wing-back set to undergo further examination.
Nevertheless, it seems unlikely that the 24-year-old will recover in time for Tuesday's qualification game at home to Northern Ireland.
Coentrao's injury is yet another blow for the former Benfica star after he was banned for four Liga games back in August, following a verbal outburst at a referee.