Manchester United reportedly had 'spies' present at Tuesday night's Champions League clash between Porto and Atletico Madrid in Portugal.
Atletico ran out 3-1 winners over the Blue and Whites to secure their spot in the knockout round of the competition as Group B runners-up.
Antoine Griezmann, Angel Correa and Rodrigo De Paul scored the goals for Diego Simeone's side, while Sergio Oliveira came off the bench to net a late consolation for Porto.
According to O Jogo, the Red Devils had 'spies' in attendance for the European contest, with the English giants keeping a close eye on the contest.
The report does not suggest that Man United were watching any player in particular, but they have previously been linked with Atletico's Jan Oblak and Marcos Llorente.
Ralf Rangnick's side could potentially draw the Spanish champions in the last-16 stage of this season's Champions League, but Porto have dropped down to the Europa League after finishing third in Group B.
