West Bromwich Albion have cut their losses on Borja Valero after allowing the midfielder to return to Spain with Villarreal.
Valero, 25, joined the Baggies from Real Mallorca for a club record £4.7million fee two years ago but struggled to adapt to life in the Premier League.
He returned to Mallorca on a season-long loan last season and has now signed for their La Liga rivals on a similar basis with a view to a permanent deal.
"After relegation in 2009 we agreed to loan Borja to Real Mallorca," sporting and technical director Dan Ashworth told the club's official website.
"On the back of an outstanding season in Spain and taking into account his professional and personal wishes, we decided to accept an offer from Villarreal.
"I'd like to thank Borja for his contribution and his professional attitude throughout the last two years."
Valero made 36 appearances for the Baggies but failed to find the net in English football.