A wildcat strike by Spanish air traffic controllers led to Pep Guardiola's side arriving at the Reyno de Navarra stadium just before the start time of 1900 GMT, forcing a 50-minute delay to the kick-off.
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Despite limited preparation time, Lionel Messi scored twice and Pedro once as the champions made it seven wins from seven on the road this season.
Real Madrid recovered from their 5-0 'Clasico' drubbing at the Nou Camp to beat Valencia, though it needed the 65th-minute sending off of Valencia midfielder David Albelda to give them the edge.
Cristiano Ronaldo settled their nerves with a goal after 73 minutes and then streaked away to notch his 16th in La Liga this season with three minutes remaining.
Barca have 37 points from 14 matches, Real have 35 and Valencia stay fifth with 24.
ATLETICO BEATEN
Atletico Madrid slumped to a 2-0 defeat at promoted Levante, making it three defeats in a week for the misfiring Europa League holders.
Defender Nano headed Levante in front from a corner after three minutes and Ecuador striker Felipe Caicedo sealed the win with a wonderful finish in the 59th.
Atletico, who lost 3-2 at home to Espanyol and Aris Salonika over the past week, stayed seventh with 20 points.
A pumped-up Osasuna made life difficult for Barca and they pressured the visitors all over the pitch in the early exchanges.
A wayward pass from Victor Valdes almost gifted the hosts a goal but Fernando Soriano's attempted lob went straight back to the keeper.
The breakthrough goal came when Messi slipped a ball through for Pedro in the 26th minute and Barca never looked back.
David Villa released Messi on a breakaway in the 65th and the World Player of the Year scampered away to make it 2-0.
The Argentine was then bundled over for a penalty in the 83rd and Messi picked himself up to score, taking his tally for the season to 15 league goals from 14 matches.
LACKED SELF-ESTEEM
Real coach Jose Mourinho left Karim Benzema on the bench at the Bernabeu preferring to strengthen his midfield with Lassana Diarra, and they struggled to break open Valencia.
"The most important thing was to win a difficult game," Mourinho told reporters.
"Conceding an early goal could have knocked out what little self-esteem we had left, and for that reason I played with another strong midfielder.
"This has been a boost to confidence after Mond
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