Pep Guardiola's side got off to the perfect start when summer signing Zlatan Ibrahimovic bagged his third goal in as many league starts after just two minutes at the Nou Camp.

Lionel Messi, who signed a new contract on Friday to remain at the club until 2016, then made it two after a quarter of an hour before a Dani Alves free-kick and a close-range Seydou Keita strike put the Catalans into a four-goal lead before half-time.

Sergio Aguero pulled a goal back for the visitors on the stroke of half-time and Diego Forlan added a second for Abel Resino's side late on.

But Barcelona's win was never in doubt and Messi grabbed a fifth deep into added time for the Catalans, who moved clear at the top of the table, at least until tomorrow's results, after preserving their 100% record in some style.

Guardiola's side had won both of their previous league matches before this one to top the league on goal difference ahead of this match.

But Atletico, who have been a difficult opponent for the Catalans in recent years, came into this match with only a point to their name following a desperately disappointing start to the campaign.

Barca coach Guardiola claimed he was wary of a wounded Atletico outfit in the build-up to this match, but he need not have worried as his side quickly took control of the game.

After Thierry Henry had rattled the woodwork, Ibrahimovic found the net moments later when he was put through by Sergio Busquets and clipped an exquisite finish past Atletico keeper Roberto Jimenez with the outside of his boot.

Ibrahimovic and Messi then both came close to a second goal for the Catalans.

But they did not have to wait long as Xavi put through Messi after 16 minutes and the Argentina winger left Roberto on the floor with a clever dummy before rolling the ball into an empty net.

Maxi Rodriguez was looking lively for Atletico at the other end, but the visitors were seeing little of the ball and found themselves three down after half an hour, when Dani Alves drove a brilliant, low free-kick into the far corner.

Keita then added a fourth with a simple finish after Messi had left Pablo and Luis Perea in his wake with a mesmerising piece of skill in the area.

Aguero grabbed a consolation on the stroke of half-time, when he pounced on a misplaced Busquets pass and raced clear to fire past Victor Valdes with consummate ease.

But there was no hint of an Atletico comeback as Barca continued to boss possession after the break.

Messi almost added a fifth 10 minutes after the break and the Argentina winger also appealed for a penalty as the Catalans continued to dominate.

There was less urgency now, though, and Guardiola's side were content to stroke the ball around against an opponent now focused solely on damage limitation.

There was a huge cheer for Andres Iniesta as the midfielder came on for Xavi after 64 minutes to make his first Nou Camp appearance this season, having missed the whole of pre-season and the opening matches of the campaign through injury after starring in Barca's treble exploits last term.

Rafa Marquez made his comeback from injury late on as well.

But the Mexican could do nothing about Forlan's strike to pull another goal back for Atletico.

Summer signing Dmytro Chygrynskiy allowed Forlan to shoot from the edge of the box and the Uruguay striker lashed home a stinging drive to give the visitors a faint hope with six minutes still remaining.

Jose Manuel Jurado then tested Valdes, but there was no time left for Atletico now and Barca wrapped up another impressive victory deep into added time, when Messi bagged his second of the night with a precise angled drive following neat approach play from Alves and Iniesta.

The win sees Barcelona move provisionally clear at the top.

But despite their perfect start, the Catalans can be caught by Real Madrid, Valencia and Athletic Bilbao, who play tomorrow.

Atletico, meanwhile, remain in the relegation zone with just one point from three and could find themselves bottom on Sunday.

That seems unlikely, however, as the side below them, promoted club Xerez, travel to the Santiago Bernabeu to face Real Madrid.