I don't think Barcelona would take the game lightly even if though they've secured the 2nd spot, but that said it's going to be tough game, but I don't Barcelona would play to lose and it might be worthy of a bet on Barcelona to win.
The same can't be said of Real Madrid who still have a champions league final coming up, I'd expect Ancellotti to rest his best players or give them a very limited time of play.
But in this case there might be a slight difference because it is certain that Villarreal also want to win the game at the end of their match even though it doesn't change their position too much but they still have a chance to play in a pretty good league.
I think Xavi should make this fun and I still feel that Barcelona will still dominate but in terms of defense Villarreal have certainly had some pretty good strategies so far