Torres injures knee against United
The Spain striker, who scored at Southampton and Hull earlier this month, came on as a late substitute for hat-trick hero Samuel Eto'o but did not last the distance due to a damage to his lateral knee ligament which means he faces "weeks" out.
Demba Ba will be given an opportunity in Torres' absence, Mourinho insisted.
Mourinho said: "It's time for Demba. It's a pity because Nando (Torres) is in a good moment, but it's time for Demba. Demba had a fantastic week; (it was) very difficult for me to leave him out of selection because he worked very, very well.
"Next matches is for Demba or Samuel. Let's go."