Rooney was left out of the starting XI for the 4-1 Premier League win over Leicester on Saturday after heavy criticism of his recent performances.
The United boss said: "Wayne Rooney is selected, I didn't decide yet if I start with him.
"He didn't train yesterday, he did just a little bit of the session on Monday. Today was the first time that he had a training session with the other players and today is the training session where the intensity and the complexity is obviously reduced because we have a game tomorrow.
"So I was completely convinced of playing him tomorrow from the beginning. But with this situation in the last couple of days I'm not sure if I'll do that because, with the situation that you create for him, I think really he can't afford to have a performance that is not really good.
"Because I'm here to protect him and not to put him in difficult situations, I have to analyse if the best thing for him is to start the game if he is not totally ready for it, so I'm going to discuss that with him and the medical staff."