كتب : Hatem Maher
Skipper Steven Gerrard and substitute Peter Crouch were also on the scoresheet while Lisandro Lopez scored Porto's only goal.
Portuguese giants Porto are on top of Group A with eight points, one ahead of second-placed Liverpool.
Marseille are third with also seven points following a 2-1 defeat to fourth-placed Besiktas, whose victory revived their hopes of advancing to the next stage. They have a total of six points.
Torres Show
Torres opened the scoring in the 19th minute when he rose unmarked to head Steven Gerrard's corner downward and into the net.
The goal is the Spanish international's first ever one in Europe's premier competition.
Superb Argentinean striker Lisandro drew Porto level in the 33rd minute.
Przemyslaw Kazmierczak made some good work down the left before providing a pinpoint cross to Lisandro, who took advantage of a terrible marking from Alvaro Arbeloa to head home.
Torres restored the lead in the 78th minute with a powerful close-range shot past Porto keeper Helton.
Gerrard made it 3-1 six minutes from time when he converted a penalty after Milan Stepanov's handball.
Crouch completed the rout three minutes later when he headed home Gerrard's corner.
Besiktas Recovery
Besiktas suffered a humiliating 8-0 defeat to Liverpool in the last matchday, but they managed to recover in style against Marseille.
Rodrigo Tello curled a free-kick over the wall and past the flat-footed keeper Steve Mandanda to put the Turks ahead in the 27th minute.
Nigerian full-back Taye Taiwo leveled the score five minutes past the hour mark with a thunderous strike.
Brazilian striker Bobo scored the precious winner two minutes from time after drilling a low shot underneath Mandanda.