Manchester United are reportedly interested in signing Porto goalkeeper Diogo Costa.
The Portuguese shot-stopper rose to prominence last season, helping his side to win the league and cup double in Portugal, as well as starting every game in Portugal's run to the World Cup quarter-finals this year.
According to Spanish outlet AS, United are yet to activate their clause to extend David de Gea's current deal, which expires in the summer.
Despite the delay in extending De Gea's stay, Man United recently used the same clause to extend the contracts of Fred, Marcus Rashford, Diogo Dalot and Luke Shaw.
The club are understood to be interested in extending his deal, but if not they are looking at Costa as a potential replacement.
However, the report claims that they would likely have to make him the world's most expensive keeper should they sign him.
Currently, that title is held by Chelsea's Kepa Arrizabalaga, who signed from Athletic Bilbao for a world-record fee of €80m (£72m).
