The 31-year-old has struggled with injuries and illness in 2017, picking up three knocks in as many months, but had reportedly recovered from his most recent ankle trouble.
Rooney trained with the rest of the squad at Carrington yesterday and was assessed during and after the session, but has not travelled to Belgium.
Mourinho admitted that the club captain is not happy with his fitness and will rest him with a view to utilising him against Chelsea at the weekend or possibly the following week.
