Zlatan Ibrahimovic made a stunning return to fitness in record time after suffering a serious knee injury, but Jose Mourinho says it is too soon to consider the Swede for a place in the starting lineup.
It seems Ibrahimovic will continue to play a substitute's role as he builds up his fitness, having returned to action against Newcastle on Saturday before coming off the bench at Basel in midweek.
"He is not ready," said Jose Mourinho. "Step by step, minute after minute, match after match. I think it is easy to play him if the team is losing, you need him on the pitch for the last 15-20 minutes."
"If the team is winning, you need him on the pitch for the last 15-20 minutes because his qualities are adapted to both situations," the United manager added.
"Normally he's going to have these periods. One day we'll feel that he is physically ready. Is his impact around the place just as important? No. It's his impact on the pitch when he plays. He is always positive and a good influence."
Ibrahimovic returned to Old Trafford receiving a huge ovation from the home crowd who are excited to see the 36-year-old back, but he will not be competing Romelu Lukaku's place in the starting lineup just yet.
"He is important on the pitch because he is one more option for us. I think it is impossible for [Rromelu] Lukaku to play every match, every minute like he is doing. We need this second option," Mourinho concluded.