Walter Mazzarri is wary of Villarreal, but feels Napoli should be proud of their progress in the Europa League.
The Partenopei were the only Italian representative to get out of the group stages of the competition this season.
"Villarreal are actually the best strongest team in the Spanish League and this speak volumes about their worth," he said.
"Moreover you have to consider that we'll be playing the second leg at their ground, which will be an intense atmosphere.
"But aside from the objective difficulty of the match, there is pride and great motivation on our part at having got to play against a team of absolute international class.
"It's a challenge of great prestige and it will take some feat to qualify for the next round, but it will certainly be an ulterior motive to find maturity and development within this group of players who have already realised a great objective."