As a result, the Red Devils vice-executive chairman is trying to make a splash in the transfer market.
Manchester United face a huge task in keeping their big players at the club in this summer transfer window, and it appears that one of them has missed out on training too.
Longstaff is being targeted after a promising campaign with Newcastle last term.
And the Telegraph say there are fears among the United hierarchy that there seems to be a specific tax just for themselves.
Initial reports have insisted the Red Devils will only consider selling Romelu for a straight cash deal which should recoup the £75m fee they spent on him.
The Old Trafford club look set to return for the defender in the coming weeks, with the Serie A side likely to demand a fee of around €50m.
Solskjaer, meanwhile, recently got tough and said United would not overpay for any player.
"You have to have the right players at the right price".
While the exit door is left unlocked at the Santiago Bernabéu, Los Blancos await Manchester United opening their own doors to begin the negotiation.
"As far as I am aware and up to now, we don't have any bids for any of our players so there's no reason to say other than Paul - or most of our players - have long contracts". United are also on the lookout for a center back and this has led them to renew their interest in Fioretina's Nikola Milenkovic.
Real Madrid are seen as the club in prime position to add Pogba, but would need to raise funds with the sale of Gareth Bale, Isco and James Rodriguez before making a concerted pursuit.