* Barca make it five wins out of five with 4-0 victory
* Misfiring Sociedad held at home by Malaga
A hat-trick from Pedro and a first-half penalty save by Victor Valdes helped champions Barcelona maintain their 100 percent record in La Liga with a 4-0 mauling of valiant Rayo Vallecano on Saturday.
Barca have 15 points from five games and are three clear at the top with second-placed Atletico Madrid, who have a perfect record of 12 points, visiting Real Valladolid later on Saturday.
Barcelona coach Gerardo Martino rotated his squad again with Dani Alves, Andres Iniesta and Alexis Sanchez starting on the bench, and his side were quickly on the back foot against their hard-running and aggressive hosts.
Valdes was called into action after only three minutes as he saved a point-blank header from Alberto Perea.
The compact pitch at Vallecas and a turbo-charged start from Rayo had Barca struggling to control an open game, with Lionel Messi and Neymar going close at one end, and Martin Montoya playing a backpass just wide of his own post at the other.
An Alex Song interception was the starting point for the opener in the 33rd minute, as he set Messi on a jinking run past two defenders, and the Argentine forward laid the ball off for Pedro to fire low into the corner
Rayo's determination was undimmed, however, and minutes later Adriano bundled over Roberto Trashorras for a penalty.
Valdes saved a penalty against Ajax Amsterdam in Barcelona's 4-0 Champions League win on Wednesday, and guessed right again as he denied Rayo captain Trashorras from the spot.
Rayo had matched Barca for possession in the first half but were caught out again as another interception saw midfielder Cesc Fabregas break down the left and cross low for Pedro to finish high into the net in the 47th.
Rayo began to run out of steam and Neymar almost bagged his first league goal for the club when he shot against the post, and shortly afterwards he selflessly squared for Pedro to tap home the third and his fifth of the campaign in the 72nd.
La Liga's leakiest defence then conceded a fourth seven minutes later after another interception on the edge of their area, and Fabregas calmly curled a shot inside the post.
Earlier, the demands of balancing domestic and European campaigns appeared to weigh heavy on Real Sociedad as they were held to a 0-0 draw at home to Malaga.
The San Sebastian-based club are back in the Champions League for the first time in a decade but suffered a shock 2-0 home defeat by Shakhtar Donetsk in their opening Group A game in midweeek.
They made a slow start against Malaga at Anoeta, with the visitors looking the more dangerous in a tight first half with few chances.
Sociedad slowly established themselves in the contest, with Imanol Agirretxe spurning a good opening and Jose Angel putting a freekick just over, but too often they were frustrated by Malaga's offside trap.
The last 15 minutes saw Malaga's Roque Santa Cruz twice go close to breaking the deadlock, and Sociedad's young boss Jagoba Arrasate will have been the most concerned at the end as his side completed a third consecutive game without scoring.
Sociedad stayed seventh with six points.
In Saturday's other game, 10-man Almeria again squandered a winning position as they lost a two-goal lead and were held to a 2-2 draw at home to Levante.