The defender reportedly has a £44 million release clause in his current contract.
Since 2015, the Albanian international has been an ever-present in their line-up since and has made 134 appearances for the club in all competitions.
He has been a regular starter for the Albanian national team as well and has won 37 caps for his country. His current contract with Napoli ends only in 2021.
Red Devils’ current Right-back Antonio Valencia may still have a couple of seasons in him.
But according to Italian transfer reports Mourinho has identified him as a future replacement.
Napoli may sell him if United are ready to pay his release clause and if the player is also willing to move.