Manchester United have reportedly moved a step closer to completing the signing of Porto defender Diogo Dalot.

According to Sky Sports News, the Portugal Under-21 star has successfully completed a medical at Old Trafford.

United are said to view the highly-rated young right-back as a potential understudy to Antonio Valencia.

Juventus, Napoli and Real Madrid are also reported to have monitored Dalot during his first full season in the Porto senior side, during which he won the league with the Portuguese giants.

The defender could become United's second summer signing following confirmation that the club have reached a deal with Shakhtar Donetsk to sign midfielder Fred.