The Chilean scored a stunner early in the first half for the visitors, as Wakaso Mubarak's red card left the hosts with little hope of a comeback, before the Spaniard sealed it
Alexis Sanchez opened the scoring in sublime fashion after a quarter of an hour for the visitors, who were largely in control for the majority of the game, before Wakaso Mubarak's red card with 10 minutes to go essentially ended any hopes of an Espanyol comeback.
And in the 86th minute, substitutes Xavi and Pedro combined excellently for the latter to poke home the clinching goal, Barca's 52nd away from home this season - marking a new record in the Spanish top flight.
And another landmark looms, as the Blaugrana's triumph in the Derbi Barceloni moves them to within three points of Real Madrid's 100-point tally from last season - which will be met should they beat Malaga in their league finale next Saturday.
Sanchez was joined in the forward line by Cesc Fabregas and David Villa; three players whose sub-par campaigns have seen them face uncertain Barca futures - particularly with the arrival of Neymar from Santos.
But Sanchez could hardly have done more to convince Tito Vilanova of his worth to the team next season than his fantastic moment of individual brilliance to get the ball rolling after 14 minutes.
The Chilean seemed to be running into a dead end after playing a one-two with Villa, but with supreme agility, he evaded two quick-fire challenges from Diego Colotto and Raul Rodriguez, before bending an exquisite finish into the far side.
It was a fairly comfortable opening to the game for Barca, though as expected, Lionel Messi’s absence denied their attack a certain element of panache, as Espanyol were able to hold their ranks at the back.
The stadium was then united in a minute of applause after 22 minutes, to commemorate former player Dani Jarque, who passed away in 2009 with a heart attack at the age of 22.
Espanyol, however, could count themselves lucky not to have conceded a second goal just after half an hour, when Alex Song clipped a beautiful pass over the top of the defence to former Arsenal team-mate Fabregas, whose effort struck the post.
Andres Iniesta also came close to notching his team’s second goal with a powerful strike that whistled the wrong side of the post moments before the interval.
Though the hosts played with more poise after the restart, it was Villanova’s men who nearly struck first in the second half. A brisk move on the edge of the 18-yard area found Villa in space 12 yards out, but the striker could not find the target.
But the second half had a distinct ‘end-of-season’ feel, as Barca seemed in no hurry to extend their lead, while Espanyol could not find an extra gear in the attacking third.
However, the game was thrown right back into the fire in the 80th minute when Wakaso picked up a yellow card, protested furiously, and was promptly given a second booking to put an end to his night.
The home fans, already testy after a few perceive refereeing injustices, were brought to their feet in fury by the Ghanaian’s dismissal, but were silenced for good with four minutes remaining as Barca struck again.
Xavi played the ball high into the path of Pedro inside the area, and the forward took the pass in his stride to flick a wonderful finish into the back of the net, and kill off the game for good.