La Liga wrap: Barca go 11 points clear
Barcelona preserved their unbeaten start to the season with a 4-0 victory over Espanyol, while Real Madrid also won in a thriller.
A sublime opening half-hour from the home side did the damage, with Xavi opening the scoring after just 10 minutes at Camp Nou.
Pedro soon netted a double before Lionel Messi converted a penalty after Cesc Fabregas was brought down in the area.
With manager Tito Vilanova back on the touchline after surgery for cancer, Barcelona were seemingly buoyed by his return as they broke the deadlock through Xavi, who slotted home unmarked.
The hosts' were unrelenting and after Kiko Casilla made a great save to deny Iniesta in the 13th minute, it took just another two minutes for the second to come as Pedro sent the ball into the far corner of the net.
Midway through the half Sergio Garcia blazed a golden chance to halve the deficit over the bar and it proved costly as Pedro added Barcelona's third in the 27th minute.
And it went from bad to worse for the visitors with Messi netting his 27th La Liga goal of the season two minutes later.
Victory moves Barcelona 11 points clear at the top of the table following Atletico Madrid's 1-1 draw at Mallorca.
Defending champions Real Madrid secured a priceless 4-3 victory over Real Sociedad in a pulsating clash at the Bernabeu, despite playing most of the match with 10 men.
Jose Mourinho's men took the lead two minutes into the game through Karim Benzema before goalkeeper Antonio Adan was dismissed for a challenge inside the penalty area.
Xabi Prieto scored the resulting spot-kick to level proceedings but the hosts' restored their advantage in the 35th minute through German midfielder Sami Khedira.
Prieto levelled five minutes before the half-time break, however a quick-fire brace from Cristiano Ronaldo put the home side two goals ahead with 20 minutes left to play.
Sociedad, however, ensured a nervy finish as Prieto completed his hat-trick 14 minutes from time before their hopes were dashed when Daniel Estrada saw red for a second bookable offence.
Meanwhile, Iago Aspas bagged a first-half brace to help Celta de Vigo to a 3-1 victory over Real Valladolid.