Marco Ruben's first-half goal proved decisive at El Madrigal as Villarreal won 1-0 over PAOK Salonika.

The Argentinian striker broke the deadlock seven minutes before the break to secure the Spanish side their second straight win in Group D and end their Greek rivals' unbeaten start.

With the evening's other game in this group ending goalless between Dinamo Zagreb and Club Brugge, Villarreal climbed atop the pool by two points.

The Yellow Submarine had the better of the early exchanges but struggled to break down a stubborn PAOK defence.

Ruben got himself into a good position just before the half-hour but saw his left-footed effort from close range blocked by PAOK defender Bruno Cirillo.

The breakthrough arrived in the 38th minute, when Ruben fired into the bottom-left corner from the right side of the penalty area from Giuseppe Rossi's pass.

PAOK, who parted company with coach Pavlos Dermitzakis last weekend due to poor domestic form, almost hit back immediately when Zlatan Muslimovic met Giorgos Fotakis' inswinging corner, but he sent his far-post header wide.

There was still time for Juan Carlos Garrido's side to pass up an opportunity to extend their advantage before the half-time whistle, Rossi lashing wide from 12 yards two minutes before the break.

The hosts continued to boss the encounter in the second half but could not add to their lead.

Rossi tried his luck from long range but could only direct his effort wide, while at the other end Giorgos Fotakis let fly from distance but failed to trouble Diego Lopez.

PAOK needed Cirillo to get his body in the way to block Cani's blast midway through the second half to keep the deficit at 1-0, but they were offering little as an attacking force.

Vladimir Ivic's volley flew over the bar in the 71st minute and Nabil El Zhar's attempt three minutes later went the same way as the visitors tried in vain to get back on level terms.

Cani went close to grabbing a second goal two minutes from time with a left-footed shot from 12 yards, but PAOK goalkeeper Dario Kresic got down to tip it around the post.

Nilmar also fired wide and substitute Jozy Altidore was denied by Kresic in stoppage time, but the second goal was not forthcoming.