They aren’t currently training with Man United’s first-team and allegedly haven’t been told they will play a role in Mourinho’s plans at Old Trafford.
Mourinho has been keen on promoting youngsters from the club’s academy, but has identified central defender Axel Tuanzebe and full-back Timothy Fosu-Mensah as stronger options to be involved in the first-team.
The Portuguese boss is said to believe they possess much greater potential for development and will be give opportunites on his side this season.
Blackett joined Celtic on a season-long loan deal last term but only made four starts for the Scottish side. Mourinho made centre-back Eric Bailly his first signing at the club and Blackett will find it hard to secure first team opportunities so it looks like a loan move would benefit him.
As well as Darmian, Varela is competing with Antonio Valencia and Ashley Young for a spot in defence. He performed well over the festive period but there is a question mark over whether he has the quality to make himself a long-term success at Old Trafford as Mourinho now believes he’d be better suited elsewhere.
Fosu-Mensah broke through to the first-team ranks last season and made 10 appearances for the senior side proving his talent across the back four. He held his own against the likes of Arsenal, Manchester City and Everton last season and is a very talented youngster.
Tuanzebe has also been a key player for United’s U21 team, although is yet to make his full first-team debut, but it it looks like he may be rewarded with his opportunity under Mourinho.