Villarreal are in the market for a central defender and have been linked with Francisco Pavon and Carlos Cuellar.
The Yellow Submarines have already invested heavily this summer having brought in Robert Pires, Nihat Kahveci, Cani and Jose Enrique.
However, they suffered a major blow last weekend as they were knocked out of the Intertoto Cup by Slovenian outfit NK Maribor meaning they will not now play European football this season.
Coach Manuel Pellegrini clearly feels he still needs to strengthen his backline going into the new campaign and is looking to bring in a strong, young centre half.
Cuellar and Pavon have emerged as potential targets, although the availability of both players is unclear at the moment.
Pavon could well be deemed surplus to requirements at Real Madrid following the arrival of new coach Fabio Capello having failed to establish himself as a first-team regular at the Santiago Bernabeu in recent seasons.
Cuellar is very much a fixture in the first team at his club Osasuna and the Navarran outfit would want a substantial fee if they were to be persuaded to sell.
However, the 25-year-old only has 12 months left on his current deal at the Estadio El Sadar meaning Osasuna could be forced to consider a sale if he refuses to sign a new deal.