The midfield pair both miss out through injury, but on the plus side for the Spaniards, Cristian Zapata and Javier Camunas are available for selection once again
Cani has been ruled out with a minor knee injury, while Valero has been laid low by a gastrointestinal problem.
However, according to the club’s official website, both midfielders could yet return in time for this Sunday’s La Liga match against Real Sociedad.
On the plus side for the Yellow Submarine, defender Cristian Zapata has recovered from knee ligament damage and is available to face the Italians.
Midfielder Javier Camunas is also back in the mix after a spell on the sidelines with bruising to his right fibula.
Villarreal go into the clash against the Partenopei with nothing to play for after losing their five previous games in Group A.
Napoli, though, will guarantee qualification for the knockout stages as runners-up at the expense of Manchester City if they defeat the Spaniards.