The pressure had been on new Barca coach Pep Guardiola following a return of just one point from their opening two games but the Catalan giants were back to their free-flowing best in Gijon.
Xavi and Samuel Eto’o gave Barca a commanding half-time advantage and an own goal from Jorge Garcia further strengthened their position.
Although Francisco Maldonado pulled one back for Sporting immediately, the hosts’ task was rendered almost impossible by the sending-off of Gerard.
Barca took full advantage of their numerical advantage with Andres Iniesta and a late double from Lionel Messi sealing an impressive win.
Guardiola’s side are up to mid-table, three points behind a four-way tie for top spot.
Valencia sit atop the pile after an 83rd-minute Juan Mata goal saw them beat Osasuna 1-0.
Almeria, in second, also left it late to beat Malaga with Alvaro Negredo netting with 15 minutes to go to settle a bad-tempered derby which saw both sides finish with 10 men.
Villarreal are third and Espanyol fourth.
The Yellow Submarine won 2-1 at Numancia on Sunday, goals from Santi Cazorla and Joseba Llorente seeing them to victory after Gorka Brit had put the home side in front on the stroke of half-time.
Espanyol were the overnight leaders despite being held to a 1-1 draw at home to Getafe on Saturday.
Sergio Sanchez grabbed a point for the Barcelona side just before the hour mark after Manu had put the visitors ahead two minutes into the second half.
Real Madrid are on the coat-tails of the leaders after a 2-0 win at Racing Santander.
It was another unconvincing display from Bernd Schuster’s side but they claimed all three points thanks to second-half goals from Ruben De la Red and Ruud van Nistelrooy.
The Seville derby, between Real Betis and Sevilla, ended goalless, as did the meeting of Deportivo La Coruna and Real Mallorca at the Riazor, while Athletic Bilbao enjoyed a maiden win after edging out Real Valladolid 2-0.
Fernando Llorente put the Basque side ahead five minutes into the second half and an Andoni Iraola penalty with seven minutes to go settled matters.
In Saturday’s other game, Atletico striker Florent Sinama-Pongolle scored a brace against former club Recreativo Huelva as Los Rojiblancos romped to a third successive 4-0 home win.
The absence of injured frontman Diego Forlan was all but forgotten in the seventh minute when Sergio Aguero opened the scoring.
Maniche doubled the lead shortly after the interval before Sinama-Pongolle added gloss to the scoreline with goals after 78 and 89 minutes to secure the points.