Phil Jones and Henrikh Mkhitaryan are included in the Manchester United squad heading to Turkey for Thursday's Europa League clash with Fenerbahce.
United are second in Group A, level on six points from three games with leaders Feyenoord, while Fenerbahce are third with four points.
Defender Jones has not made a competitive appearance for United since January, but having recovered from a knee problem he could get a run out on Thursday.
"It has been a difficult period for him, but he has worked hard to recover, he is training with the team for more than a week now and we are in a difficult situation because we lost three defenders in a week," Mourinho said of Jones.
"Because of that, we don't have more time to give him to be in better condition - we have to select him and maybe we have to play him."
While United have won just two of their last six matches, Dick Advocaat's Fenerbahce have suffered just one defeat in their last nine matches.
Chris Smalling, Michael Carrick and Memphis Depay will miss the Europa League clash with Fenerbahce.
Jones, back from a knee injury, is part of the 21-man travelling party 10 months after his last competitive appearance, as are Anthony Martial, Tim Fosu-Mensah and Henrikh Mkhitaryan having missed recent squads.
Smalling (foot) joins Antonio Valencia (arm) and Eric Bailly (knee) in staying at home, while Carrick and Depay have also stayed in the north west.
Fenerbahce have alternated between defeat and victory in their five previous meetings with Manchester United, losing the reverse fixture two weeks ago.
The Red Devils have won one and lost one of their two previous away trips to Fenerbahce, losing 0-3 last time out in December 2004.
Fener have won just four of their 18 games in all European competitions against English sides (D3 L11), with half of those victories coming against Manchester United.
Manchester United have won three of their last five visits to Turkey in European competition (L2), though they did lose on their last trip there (0-1 vs Galatasaray in November 2012).
The Turkish side are unbeaten in their last five home games in the Europa League (W4 D1), keeping a clean sheet in each of their four victories.