Ruben Amorim has admitted that, although Amad and Matthijs de Ligt are not fit enough to start Thursday's game at Athletic Club, they could still be involved in Bilbao.
The pair took part in Wednesday's open session at Carrington and were part of the 26-man group that flew to Vitoria Airport later in the day.
Amorim has selected a larger squad than usual, as United will stay in Bilbao to train on Friday, but he is not taking any risks with the two returnees.
Amad hasn't featured for almost three months, since picking up an ankle injury after our victory over Leicester City in the Emirates FA Cup, while De Ligt has spent a month on the sidelines after getting injured during the 1-0 league defeat at Nottingham Forest.