Watford have confirmed Ecuador left-back Pervis Estupinan has joined Villarreal for an initial fee of £15m.
The 22-year-old joined the Hornets in 2016 but did not made a senior appearance and spent last season on loan at Spanish La Liga club Osasuna.
His 36 appearances and one goal helped them secure safety in their first top-flight season.
Estupinan has also had previous loan spells in Spain's top two divisions at Granada, Almeria and Real Mallorca.