Jose Mourinho said off-season recruit Henrikh Mkhitaryan is close to returning to the Manchester United side after he was absent for Thursday's Europa League clash.
Despite reports he would be included in United's matchday squad, Mkhitaryan was left out as Mourinho's men eased past Fenerbahce 4-1 at Old Trafford.
Mkhitaryan has not featured since United's Premier League derby loss to Manchester City on September 10 due to a thigh injury but Mourinho insisted the Armenia captain is edging closer to a comeback, having taken part in a strenuous training session on Thursday.
"The situation is that we played with [Jesse] Lingard, with [Juan] Mata and [Anthony] Martial," Mourinho told reporters as he revealed the reason behind Mkhitaryan's absence.
"I am not an Einstein, I don't know a tactical system to play with four wingers at the same time. He has to work more to get the intensity and the real fitness to play at the high level.
"To have him here tonight on the bench and to give him 15 to 20 minutes, like I did with Memphis [Depay], I thought it would be better for him to work the way he did yesterday and much harder, obviously.
"I thought it would be much better for him to work today, like he did in the specific session, than to wait for his chance. But he is ready. He is ready very soon."
United travel to Stamford Bridge to face Chelsea in the Premier League on Sunday.