Manchester United reportedly had scouts in attendance for Saturday night's Portuguese league match between Porto and Benfica, which ended in a 3-2 victory for the home side.
Carlos Vinicius scored twice for the visitors but Porto picked up all three points to move to within four points of Benfica at the top of the Primeira Liga table.
United signed Bruno Fernandes from Sporting Lisbon during the January transfer window and have previously secured deals for the likes of Cristiano Ronaldo and Nani from Portuguese football.
According to O Jogo, the 20-time English champions had scouts in attendance for Saturday's league contest, although the report does not mention whether there was a specific target for the club.
United have previously been linked with Benfica's Ruben Dias, though, and the centre-back scored an own-goal for his side in their narrow loss at Estadio Do Dragao.
Ole Gunnar Solskjaer's side will be looking for just their second league victory of 2020 when they travel to Stamford Bridge to face Chelsea on February 17.
