Manchester United beat local rivals Manchester City to the signing of the Brazilian midfielder from Shakhtar Donetsk but the move hasn’t worked out for the 25-year-old.
Fred has started just three of United’s 14 games in all competitions and made just seven Premier League appearances this season being left out of the squad for the 2-2 draw with Arsenal.
And Mourinho, whose side are down in eighth in the Premier League with a goal difference of minus one, claimed he cannot use Fred until United become more solid defensively.
Asked how he felt Fred had adapted to life at United, Mourinho said: “Step by step. You have other players at other clubs who needed time and some of them played even less than Fred.
“I think Fred, when the team is defensively stronger and doesn’t need in midfield people that are more worried in giving some balance to the team than being involved in creation and the attacking dynamic, the day we are stronger defensively, I think the horizons for Fred change completely.”
United will next host bottom club Fulham, looking for their first Premier League win since their last-gasp 2-1 victory at Bournemouth back on November 5.