Manchester United have made an official approach to sign young Benfica defender Ruben Dias, according to a report.

The Red Devils are believed to have sent chief scout Marcel Bout to watch the 21-year-old centre-back, along with teammate Joao Felix, in action last week.

Portuguese newspaper Record claims that United have now opened negotiations with Benfica over a move for Dias, who has made 54 Primeira Liga appearances for the Eagles since the start of last season.

However, United face competition from Juventus for the nine-cap Portugal international as the Italian giants are already at an advanced stage in the negotiating process.

Dias is rumoured to have a £51m release clause in his contract, which the Premier League side are tempted to trigger to beat Juve to the punch.