Last night saw Guardiola's men rampant against Atletico Madrid at the Nou Camp, running out 5-0 winners on the back of a hat-trick from Lionel Messi - seven days after an 8-0 trouncing of Osasuna.

Barcelona lost a pair of matches on their pre-season tour of the United States, and a team of reserves were beaten by Espanyol in the Catalonia Cup final.

But Barcelona`s main men can be imperious, and Guardiola acknowledges that.

But he also suggests his team are there to be taken down a notch if they let their standards slip.

A pair of 2-2 away draws against Valencia and Real Sociedad might be taken as signs of weakness, and those results have contributed to Barcelona lying behind leaders Real Betis in the early Primera Division standings.

"We are not unbeatable ... any team can beat us," Guardiola said.

"But if we do things right the fans who come to watch us will have a good time, which is the most important thing."

Reflecting last night on the comprehensive victory over Atletico, Guardiola said: "We played very well, it was a lesson in concentration, but from tomorrow on we have to do it again. Let's see if we're able maintain this level. It's this year's challenge."

He told his post-match press conference - according to Barcelona's official website - that Messi's latest masterful performance spoke for itself.

"Messi was decisive again, you can only congratulate him. He's a player that you don't have to explain, you just have to watch him in action," Guardiola said.