Zaragoza came into the match having taken just 27 points from 30 matches and occupying 18th place. And its performance replicated its standing as Barcelona -- 13 points clear of second-placed Real Madrid -- dominated from the start.
Barcelona made seven changes from the side that progressed to the Champions League semifinals this week.
Zaragoza, which has not picked up a win since mid-December, made three changes from the side that lost at Deportivo La Coruna, with Edu Oriol, Christian Romaric and the suspended Abraham all missing out.
Tello fired a warning to the Zaragoza back line after 16 minutes when he shot over from 20 yards and three minutes later the visitors were ahead when Thiago found the bottom left-hand corner from just inside the area.
Helder Postiga had the chance to register the home side's first decent effort on goal after 25 minutes, but from 18 yards out he mishit his effort.
Barcelona was more ruthless and six minutes before the break Tito Vilanova's team was two up. Tello combined brilliantly with Thiago to open up the Zaragoza defense before placing a curling effort past Roberto and into the bottom corner.
Barcelona started the second half almost as strongly as it had finished the first with Alexis Sanchez hitting the bar after 46 minutes with a lobbed effort from 18 yards.
After just 53 minutes they were three up when Tello cut in from the left and, after easing past Apono, he fired across Roberto and into the net.
Roberto was called into action once more in the 69th minute, tipping over Tello's lob and then catching Fabregas' shot from the following corner.
Apono and then fellow sub Ruben Rochina shot over for Zaragoza, before Paco Montanes somehow managed to miss the target from six yards, with his effort summing up Real's evening.