Manchester United reportedly had a scout present to watch Benfica defender Ruben Dias over the weekend.
While United added Harry Maguire to their ranks earlier this summer, there remains a desire to sign another - preferably younger - centre-back.
The Premier League giants have been linked with 22-year-old Dias, who is expected to make the switch to a bigger club in one of the upcoming transfer windows.
According to Record, United sent a representative to assess the development of the Portugal international in Benfica's fixture with Gil Vicente.
Dias, making his fifth successive league start of the campaign, played the full 90 minutes as Benfica registered a 2-0 victory.
There are still just under five years remaining on Dias's contract, although the prospect does possess a release clause, currently set in the region of £57m.