Manchester United were reportedly among a number of clubs who had scouts present at Porto's fixture against Pacos de Ferreira last weekend.
Many of European football's top clubs are already making plans ahead of the summer transfer window and it should come as no surprise that players from Porto may be targeted.
The Portuguese giants are unbeaten in Primeira Liga this season, winning 21 of their 25 matches to establish a six-point lead at the top of the standings.
On the back of Liverpool pouncing to sign Luis Diaz in January, A Bola says that other key men are receiving attention ahead of the next campaign.
With 24 goals contributions in as many top-flight appearances, Mehdi Taremi may have been among the players whose performance was being assessed.
Leicester City and Atletico Madrid are also said to have had representatives at Estadio Capital do Movel.
