Barcelona are now four points adrift of leaders Real Madrid after a 0-0 draw at Getafe on Saturday.
The Blue and Whites are up to sixth after a 1-0 win against Celta de Vigo on Saturday, Samuel scoring the only goal of the game in the 21st minute.
Two goals from Feghouli and one from Piatti were enough to see Valencia cruise past Rayo Vallecano, 3-0 the final score.