The Chilean and the Spaniard both hit the net in a straightforward victory in the Estadio da Luz, although an injury to the defender and Busquet's red left a sour taste.
A smart close-range finish in the opening stages from Alexis gave his side the perfect start, before Fabregas ensured that Barca would be returning to Camp Nou with all the points when he blasted home 10 minutes into the second period. However, Puyol fell awkwardly on his arm in the closing stages, and is now a doubt for this weekend's Clasico clash against Real Madrid.
With both teams coming out in attacking fashion, a capacity crowd in the iconic Estadio da Luz enjoyed a gripping start to the group stage encounter. Looking to hit quickly on the counter, Benfica quickly called Victor Valdes into action when the goalkeeper was forced to parry away Bruno Cesar's low effort from outside the area. Barcelona's response, however, was as lethal as it was rapid.
With just six minutes on the clock, Lionel Messi took advantage of some slick passing in midfield as he was released on the left-hand side of the penalty area. The Argentine slid the ball straight into the path of Sanchez, who steered it past the stranded Artur to give the Catalan side the lead. Benfica looked to hit back as soon as possible, and only a fine save from the legs of Valdes denied Lima after the striker was played in by a fine pass from Nicolas Gaitan.
Barca moved on to enjoy a predictably dominant share of possession, and could have extended its lead on two golden occasions. In an almost mirror image of the opener, Messi this time took advantage of Alexis' low cross to move in on goal, but 'La Pulga' was denied by a fine save from Artur. It was then the Chilean's turn to threaten. Sanchez did well to control a piercing long-range pass from Xavi and take aim, but with the ball still bouncing the ex-River man's half-volley flew just over the bar.
The closing stages of the first half were marked by some scrappy passages from both teams, with heavy tackling and the odd moment of theatrics making it a busy evening for referee Cuneyt Cakir. Barcelona would have hoped to go in to the break with a stronger advantage than Alexis' solitary effort, but in spite of creating the best chances of the half had to settle for a slender lead as the teams went into the dressing rooms.
With barely a minute on the clock following the restart, the away team could and should have doubled its advantage. Alexis was again let through after drifting away from Maxi Pereira on the right, but the 'Nino Maravilla' saw his effort fly wide of the post to once more let Benfica off the hook. The Chilean was causing all sorts of problems for the host, who looked far too stretched in following Barca's pinpoint passing across the field.
A goal looked inevitable as the whistles of the home crowd welcomed Barcelona's miserly control of the ball, and it duly came through Fabregas. A dizzying run from Lio Messi opened up the Portuguese defense, and the Rosario native picked up his second assist of the evening as his deft through ball was blasted home by the midfielder.
From that point onwards, there was only to be one winner. Benfica continued itsvaliant attempt to get back into the game, but the best chances were still falling to those in the Blaugrana. Pedro went close to claiming a third for his team, but was frustrated by Artur after slipping in neatly behind the defense. Picking up the rebound, Messi somehow ghosted past three defenders in close attention, only to see his own effort blocked.
The rest of the game was a formality, although Barca hearts were once more left in their mouths when Puyol screamed out in agony after a heavy fall in the penalty area. The central defender, having just returned from injury, was taken off for Song in what could be a major blow for the away team days from the Clasico. The scare was a black mark on what was otherwise an accomplished Barca performance, as was a late red for Sergio Busquets following a seemingly innocuous clash with Maxi Pereira as they continued their perfect start to the Champions League at the expense of Benfica.
The win means Tito Vilanova's men have picked a maximum of six points in their opening two Group G encounters, extending their winning run in all competitions to six games. The Blaugrana move above Celtic to the summit of their group, while Benfica lies in third with one win and one defeat.