Barcelona's perfect start to the Primera Liga season is set to be severely tested over the coming week as they face two of the toughest fixtures on the calendar.
This Saturday they travel to unbeaten Sevilla and then, after a midweek Champions League trip to Benfica, Tito Vilanova's men host arch rivals Real Madrid at the Nou Camp.
Having already built up an eight-point lead over Jose Mourinho's men, a victory in El Clasico could leave Madrid's title hopes in serious trouble, although Barca midfielder Sergio Busquets insists it would be foolish to rule out the champions at this early stage.
"Nobody expected this advantage in so few games, but we are only at the start of the season and Madrid are capable of going the rest of the season without losing," the Spain international said in El Mundo Deportivo.
Busquets is also reluctant to think too much about El Clasico when his side have a tough trip to Sevilla coming up beforehand.
Sevilla have picked up three wins and two draws from their five matches so far, including a home victory over Madrid.
Busquets said: "Sevilla is a very difficult ground to go to and the team is doing very well, as we saw against Madrid. With Michel they are much better, much fresher.
"They know what they want to do and it's going to be difficult to get the three points, although that's what we will aim to do.
"Regardless of whether Madrid are our next opponents, it's a difficult game."
Sevilla midfielder Ivan Rakitic is optimistic his side can end Barca's 100% start, saying on SFC TV: "We can win this and any game.
"We're playing the best team in the world but we're not going to make it easy for them. We know we can win this game."
Should Barca slip up, Madrid will expect to take advantage when they host promoted Deportivo La Coruna on Sunday.
Madrid have had an inconsistent start to the campaign but they now look to be clicking into gear after following up their stunning Champions League victory over Manchester City with a 2-0 derby triumph at Rayo Vallecano on Monday.
Madrid then thrashed Millonarios 8-0 in the Santiago Bernabeu Trophy last night, with out-of-favour Kaka giving Mourinho a reminder of his talents with a hat-trick and a man-of-the-match performance.
Mourinho admits the Brazilian and some of the other fringe players had pushed their cases for inclusion in the first team, saying: "Kaka and the others have done enough for me to think about them and have them in mind when it comes to making the squad list."
Barca's closest challengers at the top of the table are a side from the capital, but it is Atletico showing their neighbours the way with a hugely impressive opening few weeks.
The Rojiblancos, inspired by Radamel Falcao who leads the scoring charts with seven goals, are two points adrift of Barca as they seek a fifth successive league win when they travel to second-bottom Espanyol.
Third-placed Real Mallorca travel to Getafe on Monday night while fourth-placed Malaga, who are level with Mallorca and Sevilla on 11 points, are at home to Andalusian rivals Real Betis.
In other games, Real Sociedad take on Basque rivals Athletic Bilbao, Valencia host Real Zaragoza, Celta Vigo go to Granada and bottom side Osasuna meet Levante.