Sporting Lisbon want Manchester United to subsidise Marcos Rojo's wages if they want to include the defender in the deal to sign Bruno Fernandes.
The Red Devils had offered up Rojo, Joel Pereira or Angel Gomes in the package for the Portuguese playmaker, who is valued at around £50million plus add ons.
United are ready to table a bid worth £65m later this week as they look to wrap up a deal for Fernandes this month.
Negotiations with Sporting and the player's representatives continue, and it is claimed in Portugal that Rojo could be included in the package for the 25-year-old.
The Argentinian has been deemed surplus to requirements at Old Trafford, having made just three Premier League appearances all season.
However, Portuguese publication Ojogo report that Sporting want United to cover some of the defender's wage packet.
The uncertainty over his future would seem to have had little impact on Fernandes, who starred in Sporting's 3-1 win over Setubal on Saturday, scoring twice.
Fernandes, who scored 31 goals last season, has 15 from 24 appearances for Sporting this term, with Tottenham also interested in signing him.
Sporting coach Silas had claimed he is in the dark over United's interest in his star man.
Speaking after the the victory at Setubal, he said: "I can’t guarantee any of these things because I don’t know.
"I’m already thinking about the game with Benfica [on Friday] and I’m thinking about using him."
United boss Ole Gunnar Solskjaer confirmed he has the backing of the United board as he discussed a possible transfer for the 25-year-old.
Solskjaer was asked to comment on the club's pursuit of the midfielder on Saturday.
And while he refused to discuss individuals by name, he admitted that he has the backing of the board to go out and get a player of his choosing.
Solskjaer said: "Bruno Fernandes? I can't talk about individuals that play for other clubs, but I've got to say I do have backing.
"We do have backing to do something if the right thing comes up in this window. The owners, Ed, they know what we're building towards."
