Porto are on the verge of qualifying for the knockout phase of the Champions League after they beat Maccabi Tel Aviv to move top of Group G.
The Israelis, who came into this game with a goal from their first three fixtures, almost edged ahead when Tal Ben Haim II narrowly missed the target before Eran Zahavi squandered a shooting opportunity as he was dispossessed by Spaniard Ivan Marcano as he tried to take aim.
Maccabi were almost punished for their early profligacy in front of goal when Cameroonian forward Vincent Aboubakar was denied by Predrag Rajkovic.
Aboubakar missed another chance moments later when he dragged a close-range strike wide of the target, but Porto then survived a scare as Ben Haim II effort was tipped away by veteran stopper Iker Casillas.
Porto finally broke the deadlock as Andre Andre seized on a defensive mistake by Maccabi before playing in Christian Tello and the Barcelona coolly lifted the ball beyond the onrushing Rajkovic.
Tello could have scored a second before the interval, but was denied by the outstretched foot of Tal Ben Haim I, as the former Chelsea centre-back diverted his effort over the bar.
However, the Portuguese giants did double their lead when Maxi Pereira managed to deliver a cross from the right flank, which Andre headed home after getting ahead of his marker at the near post.
Porto all but sealed victory with 18 minutes left when Layun inside on his right foot and the Watford loanee calmly curled the ball beyond Rajkovic.
Tel Aviv were awarded a penalty moments later when Zahavi latched on to a through-ball before going to ground inside the area, although replays suggest that the midfielder may have made the most of any contact.
Nevertheless, Zahavi scored Maccabi's first goal of the group phase with a spot kick, which beat the despairing dive of Casillas.
However, Porto were able to hold on and take top spot in the group, ahead of Chelsea, who beat Dynamo Kiev 2-1.