A second-half strike from substitute Ricardo Quaresma secured three points for Porto in a close Champions League contest against Athletic Bilbao this evening.
The Portuguese side came close to drawing first blood with eight minutes on the clock when Danilo's inviting cross narrowly missed the head of Jackson Martinez in front of goal.
The hosts dominated the early stages but struggled to create clear-cut chances, although Bilbao goalkeeper Gorka Iraizoz was called into action to snuff out Juan Quintero's long-range strike in the 18th minute.
For all of Porto's dominance, it was the Spaniards who came closest to breaking the deadlock in the opening half-hour when San Jose's ambitious long-range strike came back off the upright.
However, moments before half time Hector Herrera raced clear of the Bilbao defence and slotted the ball home, beating Iraizoz in a one-on-one situation to give the home side the lead.
The La Liga outfit started the second half brightly, and they levelled the match in the 58th minute when Guillermo was picked out inside the box, and he kept his composure to guide in an equaliser.
Cristian Tello could have restored Porto's advantage in the 64th minute when he found space in the area, but his shot lacked conviction and failed to trouble Iraizoz.
The Portuguese side did reclaim the lead 11 minutes later in fortuitous circumstances as Quaresma's bobbling effort squirmed beneath Iraizoz and found its way into the hapless keeper's net.
Martinez missed a golden opportunity to wrap up the points late on when he skewed a shot wide from close range, but it didn't prove costly as the hosts held on for the win.