Barcelona sports chief Jordi Cruyff saw Villarreal win at Espanyol last night.
Cruyff was in the stands making a scouting check on Villarreal defensive pair Juan Foyth and Jorge Cuenca.
Barca are in the market for a new centre-half signing as they seek to replace the retiring Gerard Pique.
Foyth, formerly of Tottenham, came close to joining Barca over the summer, with his agent holding talks at the Nou Camp about a move, though nothing could be settled.
Cuenca, meanwhile, left Barca in 2020 for the Yellow Submarine.