Felix has emerged as a big target for Manchester United towards the final few weeks of the transfer window.
Erik ten Hag is desperate for attacking reinforcements and the club are discussing a deal to sign Chelsea winger Christian Pulisic on loan.
But the Portugal international is a top target and efforts are ongoing to see whether he could be signed from Atletico Madrid late in the window.
It has been claimed that Manchester United officials met the representatives of Felix in a central Madrid hotel on Tuesday.
Discussions were held over potentially taking the forward to Old Trafford before the end of the transfer window.
But they are facing an adamantly resistant Atletico Madrid who are in no mood to sell one of their top stars.
The Spanish giants are insistent that Felix is not for sale and will not negotiate any deal to move him on.
He joined Atletico Madrid from Benfica in 2019 for a €126m fee and has a €350m release clause in his contract.