The Spaniard has made just 33 league starts for Liverpool since
he joined from Espanyol for £8m in September 2008.
Riera, 27, has featured less this season than last term and has
been pushed even further down boss Rafa Benitez's pecking order by
the arrival of Argentine star Maxi Rodriguezback in January.
A source for Villarreal said: "If a deal for Riera is feasible,
we will have to explore our options."
Former Gunner Pires, 36, is set to leave El Madrigal at the end
of the season after four years at the club as his current one-year
deal comes to an end - and Riera is seen as the ideal man to
replace him on the left flank.
Sevilla are also interested in bringing Riera, who had a loan
spell at Manchester City in 2006, back to his native Spain.
