Eager to bounce back after their league phase matchday one defeat to Arsenal, Napoli started the game brightly and duly took the lead after eight minutes through Amir Rrahmani.
The defender’s initial effort from inside the box was superbly tipped onto the bar by Luiz Junior, but Rrahmani reacted brilliantly to tuck home the rebound with a composed finish.
The hosts responded well to this early setback and almost equalised just three minutes later, when Georges Mikautadze’s blistering strike was deflected narrowly over the bar.
The Azzurri came within inches of doubling their advantage midway through the first half, as Rasmus Hojlund’s header struck the woodwork, and they would quickly regret that missed chance.
Just a minute later, a dreadful attempted pass to his goalkeeper from Matteo Politano gifted Mikautadze a golden opportunity to level the game, and the Georgia international made no mistake in rounding Vanja Milinkovic-Savic and steering the ball into an unguarded net.
El Submarino Amarillo then took the lead in sensational fashion after 26 minutes, thanks to an incredible 30-yard strike from Santiago Mourino to turn the match on its head.
An entertaining first half should have seen Scott McTominay level the game before the interval, but his close-range header when completely unmarked was somehow steered wide of the target.
The second half was a much scrappier affair with both teams knowing how crucial the next goal would be, and a lack of quality from both sides in the final third saw little goalmouth action take place after half-time.
With time running out for Massimiliano Allegri’s side, Rrahmani saw an off-balance effort from inside a congested 18-yard box flash comfortably wide of the post as frustration grew in the Napoli camp.
With 10 minutes left, a darting run from Hojlund put the Danish striker in a very promising position, but his eventual effort was blocked by the oncoming Junior. With full-time on the horizon, Villarreal sealed a much-needed UCL victory after Tani Oluwaseyi’s left-footed shot from inside the box found the back of the net to spark joyous scenes amongst the home supporters.
This result means that Napoli have won just one of their last 10 games in Spain, and they will be desperate to record their first UCL win of the season next week when they host FK Bodo/Glimt.
Meanwhile, Villarreal will seek back-to-back UCL victories when they take on Liverpool at Anfield.
Flashscore Man of the Match: Amir Rrahmani (Napoli)