Napoli have left Edinson Cavani, Christian Maggio and Paolo Cannavaro on the bench for their decider with Villarreal.
Walter Mazzarri confirmed he would have to rotate the squad ahead of Monday night's top of the table Serie A clash with Milan, as his players were exhausted after their last game.
The 0-0 draw in the first leg at the San Paolo leaves the Europa League fixture wide open.
Salvatore Aronica is suspended following his late red card in that game, joining the injured Gianluca Grava and Luigi Vitale.
Cavani, Maggio, Michele Pazienza, Fabiano Santacroce and captain Cannavaro have been rested, moving Ezequiel Lavezzi into a new centre-forward role.
The defence is completely revamped with Hugo Campagnaro joined by Emilson Cribari and January signing Victor Ruiz.
Villarreal are putting a lot more of their focus into the Europa League and field a generally full-strength starting XI with Giuseppe Rossi and Brazilian Nilmar in attack.
Napoli haven't lost any of their last four matches against Spanish sides, last losing 2-0 to Real Madrid in 1987-88. However, Villarreal are undefeated to Italians on home turf with five wins and a draw.
It should also be noted the Madrigal has been a fortress in the Europa League this season with a 100 per cent record, having scored 11 times and conceded only once.
Kick-off at the Madrigal is at 20.05 UK time.
Villarreal: Diego Lopez; Mario Gaspar, Gonzalo, Musacchio, Capdevila; Santi Cazorla, Bruno Soriano, Borja Valero, Cani; Rossi, Nilmar
Villarreal bench: Juan Carlos, Marco Ruben, Catala, Cicinho, Kiko, Gullon, Mubarak
Napoli: De Sanctis; Campagnaro, Cribari, Ruiz; Zuniga, Gargano, Yebda, Dossena; Sosa, Hamsik; Lavezzi
Napoli bench: Iezzo, Pazienza, Cavani, Mascara, Maggio, Santacroce, Cannavaro