The trio all missed last Friday's 2-1 victory over Leicester City in the Premier League, with Valencia and Matic carrying minor injuries and Lingard having only recently returned to pre-season training.
Mourinho has indicated that each player is closing in on a return, but does not expect any of them to feature when United face Brighton & Hove Albion on Sunday afternoon.
At a press conference, the 55-year-old told reporters: "Lingard, Matic and Valencia are training with the team since yesterday. They are fully fit, but not yet ready to play or even be selected I think."
United suffered a 1-0 defeat at the Amex Stadium in May.