Manchester United had scouts posted this weekend for Villarreal's clash with Celta Vigo.
Spanish sources say United boss Louis van Gaal was having Villarreal striker Luciano Vietto watched. The young Argentine is also being tracked by Tottenham, Arsenal and Liverpool.
Vietto came off the bench to score in the 4-1 rout.
Also on show was Villarreal defender Mateo Musacchio, who was scouted extensively by United during Sir Alex Ferguson's time in charge.