João Félix and Matheus Cunha are players who are of interest to the Manchester club.
A bid of €50million was tabled for Cunha recently.
The bid was immediately rejected by the Madrid club.
As for Felix, Athletico have informed United that they have no intention whatsoever of entertaining any bid.
Manchester United’s negotiations have been spearheaded by their transfer Chief, John Murtough.
Murtough will now return to England empty handed as United ponder on their next move in the transfer market.