Despite the comprehensive nature of the scoreline, Gerardo Martino's men were made to work hard for their victory as they found themselves two goals down after 14 minutes.
However, Pedro struck three times in just eight minutes before the break to turn the game on its head, with Cesc Fabregas' double, including one from the spot, making life even more comfortable for the defending champions.
The victory ensures Barca top the table going into the winter break, while title rivals Real Madrid were also made to sweat as they beat Valencia 3-2 at the Mestalla.
In what was the first league game for temporary Valencia manager Nico Estevez, goals from Pablo Piatti and Jeremy Mathieu twice brought the hosts level after efforts from Angel di Maria and Cristiano Ronaldo, but the hosts were denied a point by a late goal from substitute Jese Rodriguez.
It ensured Real did not lose any further ground in the title race as they remain five points behind Barca and Atletico Madrid.
Athletic Bilbao ended 2013 in a UEFA Champions League spot after they finished the year with a 2-1 win over relegation-threatened Rayo Vallecano - Mikel San Jose and Mikel Rico the men on target
Sunday's early kick-off saw Espanyol survive a late Valladolid fightback to win 4-2 at the Estadi Cornella-El Prat.
The hosts looked to be cruising to a sixth league win of the campaign as Cristian Stuani's brace and further goals from Sergio Garcia and Victor Sanchez Mata put them 4-0 ahead with 20 minutes remaining.
However, Javi Guerra and Victor Perez made life difficult for the home side with goals in the final 15 minutes, although Javier Aguirre's men held on to secure victory.
At the Estadio de Balaidos, Celta Vigo and Osasuna played out a 1-1 draw with Emiliano Armenteros and Augusto Fernandez scoring in the first half as Javi Gracia's men were unable to take full advantage of the defeats suffered by Rayo and Real Betis beneath them.
