There are serious worries over the United striker's mood and poor form in the two games against the USA and Algeria.
Capello cannot understand why Rooney is looking like he is carrying the world on his shoulders.
He has admitted there is a problem in the striker's mind but cannot establish what is causing it.
Capello has one theory that Rooney is feeling too responsible for the team performance and that others have to help him out.
Jermain Defoe could be asked to partner Rooney in attack against Slovenia.