Chelsea’s top scorer is back in light training and Blues boss Jose Mourinho says he “has a chance” of making his comeback at Old Trafford.
Costa returned from the international break with a new injury to go along with the hamstring problem he had already been carrying.
But Mourinho said: “He has a chance, he has a little chance. He trained individually, not yet with us.
“He had to go to hospital with viral situation that we didn't manage to resolve without being in hospital over one night.
“That was before Maribor in the Champions League. Against Maribor he wouldn't have been ready from the injury, no chance.
“But being ill didn't help process recover because we didn't want him at Cobham. Medical staff had to go to his house because we didn't want to bring him here with the viral situation.”
Costa could be forced into action because Loic Remy is definitely out with a groin problem which could sideline him for three weeks.
Mourinho added: "We'll try the best result, as always. [We'll] try to play as good as we're playing and trying to play.
"We're respecting one of the best and most difficult opponents in Premier League but we're confident and in a good moment and situation.
"There's no reason for us to change our feeling. We play a big team, yes, but we're in a good moment and going to discuss the points and try the best result."