A draw and a defeat in their two opening Primera Liga games in Spain had raised doubts about the project entrusted to Barca coach Pep Guardiola. But his players responded well to the pressure to give the team a comfortable victory in the Champions League debut.

Barcelona's two domestic league games had seen them control the ball completely only to fail to turn their dominance into clear-cut chances and Tuesday's match threatened to go the same way.

The Catalans had around 70 percent of the possession. But until Rafael Marquez opened the scoring with a 21st minute header from a Xavi Hernandez corner, they had only created one chance, thanks to a Leo Messi run and left foot shot.

It was not until the half hour that the Portuguese side managed their first shot thanks to former Barca midfielder Fabian Rochemback.

From that moment Sporting were able to slow things down and the half time whistle arrived with no further change to the score.

The second period began with Sporting looking to close down the spaces in midfield and Barca found it harder to find space. But they doubled their lead after 58 minutes through a Samuel Eto'o penalty.

The Cameroun-born striker was pushed in the Sporting area, before picking himself up to score from the penalty spot.

It looked as if Barca would go on to a comfortable win. But with19 minutes remaining Tonel headed home a free kick to put Sporting back into the game. Guardiola reacted by replacing Thierry Henry with young winger Pedrito (Pedro Rodriguez).

The expected pressure from Sporting never arrived as Barca managed to retain control of the game and Xavi Hernandez made the game safe four minutes from time. Andres Iniesta crossed from the left and Xavi ran into the area to poke the ball past Rui Patricio to seal a 3-1 win.