Liverpool, Arsenal, Manchester United and Manchester City are all monitoring Porto striker Andre Silva, according to A Bola.
Silva has scored 10 goals in all competitions thus far this season and all four clubs sent scouts to watch the 21-year-old as Porto beat Braga 1-0 at the weekend.
Newcastle United and Southampton also had representatives at the match as interest in the Portugal international continues to rise.
Article continues below
CLICK HERE FOR ALL THE LATEST RUMOURS