Arsenal and Manchester United scouts were both in attendance to watch Porto striker Andre Silva in the Champions League last night, according to the Daily Express.
Silva, whose team went down 2-0 to Juventus, has scored 13 goals in the league this season and is being reportedly tracked by Chelsea and Manchester City too.
Last month Arsenal tried to sign Andre Silva during the January transfer window and had hoped to seal a £20m swoop.
Silva could be worth closer to the £50m mark by the summer following his impressive exploits in Portugal this season.
The forward has scored 21 goals in 33 appearances for club and country so far this term.