Denis Suarez's brilliant late free-kick gave Villarreal a narrow lead to take to Italy in their Europa League last-32 tie with Napoli.
A first leg of few clear chances had looked set to finish goalless at El Madrigal, but Suarez's pinpoint 25-yard effort eight minutes from time gave the Spanish side a 1-0 victory.
Napoli goalkeeper Jose Reina managed to get the faintest of touches to Suarez's dipping shot but not enough to keep it out, the ball flying into the back of the net via the underside of the crossbar.
That proved the difference between the sides as miserly Villarreal claimed their ninth 1-0 victory of the season.
Opportunities may have been few and far between in the match but there could have been a goal inside five minutes when Reina, having raced out to the right edge of his penalty area to intercept a through-ball, mis-kicked his clearance straight to Villarreal midfielder Bruno Soriano 40 yards out.
Bruno immediately laid the ball off to Roberto Soldado on the edge of the area but, with the former Spurs man seeming certain to score, Reina made up tremendous ground to race back into his box and fling himself in front of the striker's powerful drive.
That was a shaky start from the Italian side, but they recovered and went on to largely dominate the first half, certainly in terms of possession.
However, they could not do anything with it, and the closest they came to a breakthrough was on the half-hour mark when a teasing Dries Mertens cross just avoided team-mate Manolo Gabbiadini.
The opening exchanges of the second half followed the pattern of the first, with neither side looking particularly threatening, but then Napoli hit a purple patch around the hour-mark.
Jose Maria Callejon fired wide from the edge of the box before Gabbiadini drew an awkward parry out of Alphonse Areola with another shot from range.
Two minutes later Napoli created a great opportunity with Callejon being picked out unmarked at the far post, but the former Real Madrid winger could only put his sliding volley into the side-netting.
The visitors then saw loud penalty appeals for handball turned down, and after that the Villarreal defence - who boast the second-best record in the Primera Division - tightened back up and Napoli chances, even with star striker Gonzalo Higuain being introduced in the 67th minute, dried up again.
As the minutes ticked away and a goalless stalemate looking increasingly likely, Villarreal were awarded a free-kick in a dangerous position when Samu Castillejo was fouled by Mirko Valdifiori as they challenged for a high ball.
It looked as though the left-footed Bruno would take the kick, but it was right-footed Suarez - who helped Sevilla win the Europa League last season - and his pinpoint effort was too good for Reina.