Barcelona forward Pedro Rodriguez scored a hat-trick as the Catalans continued their 100 percent start to the Spanish league season with a 4-0 win away to Rayo Vallecano.

Coming after a week in which the debate has been whether or not Barca's style has altered radically under coach Tata Martino, the win will do little to answer the question either way.

Nor will it calm the nerves of those worried about Barca's at times ragged defending in this start to the season, but part of the responsibility for that must go to a small, dry and bumpy Vallecas pitch and a Rayo side who, while their legs responded, made life difficult for the champions.

Victor Valdes had been one of Barca's heroes in midweek as they defeated Ajax 4-0 and was in action again after two minutes to parry a Perea header as Rayo showed they were not along just to make up the numbers.

Leo Messi responded with a typical mazy run quickly afterwards, before setting up Neymar, whose attempt to sidefoot across Rayo keeper, Ruben, was cleared off the line.

The Brazilian wasted another chance after 18 minutes when he side-footed wide when well placed, but Barca took the lead just after the half-hour as Messi's shimmy and pass set up Pedro, who times his run to perfection before shooting past keeper Ruben.

Valdes was at his best and saved his second penalty in a week after Adriano committed a rash challenge in the Barca area, only for Trashorrras to hit the resulting spot kick at the Barca keeper, who kept his nerve and stood his ground well.

Despite going in at half time a goal down, Rayo can have felt pleased with their work but their first half efforts were undone almost from the restart as Cesc Fabrigas broke the offside trap to set up Pedro's second.

Rayo clung on to their hopes of salvaging something, but the second goal took the spark from their play and Barca began to take increasing control of the game.

Neymar hit the inside of the post just after the hour, but although he failed to score, he did set up Pedro's hat-trick with a simple pass after being set through by Messi.

Cesc finished the scoring with just over 10 minutes remaining as Barca pressure high up the field saw them rob possession to leave him with a simple finish from the edge off the penalty area.