The club from Pamplona, a town better known for its annual bull-running festival, continue to lead La Liga ahead of Barcelona and Real Madrid.
However, the Navarre club's success is based on a flawless record at their El Sadar stadium, where they have won all six matches. This afternoon they must travel to nearby Santander to play Real Sociedad seeking only their second victory on the road.
"To be honest, we have played badly away from home," said Javier Aguirre, their Mexican coach.
"We were awful against Seville and [Real] Zaragoza and had just 45 decent minutes against Barcelona. We need a massive improvement.
"Our leadership is a mere anecdote just as it would be if Barcelona or Real were in the relegation zone and I don't know how long it will last. We are a very average team if we don't battle away and run hard. We can't afford to relax."
The season's other surprise team, Getafe, host a Barcelona team fresh from successive 5-0 wins. Getafe, however, have not lost at home in almost a year.
Real Madrid, though weakened by injury, will hope to build on last week's win at Real Betis against Real Zaragoza tomorrow. Ronaldo, Zinedine Zidane, Julio Baptista, Thomas Gravesen and Ivan Helguera are all injured and Pablo Garcia is suspended.
In two other intriguing fixtures, rejuvenated Villarreal host regional rivals Valencia and the bottom two, Espanyol and Athletic Bilbao, meet at Montjuic. Bilbao will hope that inviting Javier Clemente to take charge for the third time in his career will pay off.
In the Bundesliga, the top two meet tonight with Werder Bremen aiming to end Bayern Munich's perfect record - five wins, no goals conceded - since moving to the Allianz Arena.
Leaders Bayern have an injury doubt over Michael Ballack and a mental one over Roy Makaay. Ballack suffered a bruised right thigh in the midweek defeat to Juventus while Makaay has not scored since August.
"Roy has a problem in his head," said coach Felix Magath. "He missed a chance against Juventus that he would have taken before without doubt. I mean no reproach, though. His place is not under question."
Juventus' domestic primacy is also under threat having lost at Milan last week. Should they fail to see off fifth-placed Livorno, and Milan defeat inconsistent Udinese, the latter could go top.
Milan, who have won seven successive Serie A matches, have Cafu, Alessandro Nesta and Marek Jankulovski back from injury.
In France, the leaders Lyon, who are nine points clear in Ligue 1 and unbeaten in regulation time in 19 matches this season, play Toulouse.
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