Pep GuardiolaÃ¢â‚¬â„¢s side came into the game two points behind Real following their 1-0 victory over Racing Santander and were missing several first team players, including joint top-goalscorer Zlatan Ibrahimovic.
The loss of the imposing Swede proved pivotal as Barcelona appeared to lack an attacking spearhead to convert their dominance of possession into a commanding lead.
Thierry Henry was rested following the furore of his part in FranceÃ¢â‚¬â„¢s controversial World Cup play-off qualification and Guardiola opted to start the diminutive trio of Andres Iniesta, Pedro and Lionel Messi in BarcelonaÃ¢â‚¬â„¢s frontline.
The Catalan club began brightly with Messi forcing Athletic goalkeeper Gorka Iraizoz into the gameÃ¢â‚¬â„¢s first save on five minutes, the 28-year-old got down well to stop the low effort from the edge of the box following XaviÃ¢â‚¬â„¢s lay-off.
The two combined again in a move that should have sent Barca into the lead ten minutes later.
Xavi sent Messi through with a clear run on goal and the Argentine superstar shaped to curl the ball left-footed into the far corner but struck the ball too close to Iraizoz and he managed to block the effort.
A minute later, Barca passed up another chance. This time Saydou Keita Ã¢â‚¬â€œ who has proved deadly in front of goal this season Ã¢â‚¬â€œ rose high to head MessiÃ¢â‚¬â„¢s cross just inches wide of the far post.
Barcelona were rampant and a clever interchange between Iniesta and Messi saw the 22-year-old trick his way to the by-line before delivering a dangerous ball across goal that could only be scrambled over the bar for a corner.
Athletic were desperate to diminish MessiÃ¢â‚¬â„¢s influence on the game and Fernando Amorebieta almost ended his game by raising his studs after clearing the ball for the Argentine Ã¢â‚¬â€œ forced forward by momentum Ã¢â‚¬â€œ to clatter into face first.
Amorebieta went unpunished, but fortunately Messi returned to the game with just a grazed eye to show for the collision.
A misplaced Athletic pass on the half-hour mark allowed the recovered Messi to race through and beat two better-placed defenders to the ball before skipping wide of the on-rushing Iraizoz and curling a ball with the outside of his left boot into the path of the arriving Xavi at the far post, but the Spain talisman could only thrash the ball high and wide.
Despite BarcaÃ¢â‚¬â„¢s dominance, Athletic should have gone into the half-time break with the lead.
Francisco Yeste whipped in a cross to the far post onto the head of the unmarked Javi Martinez, but his downward header bounced wide of Victor ValdesÃ¢â‚¬â„¢ left-hand post.
Barcelona managed to break the deadlock on 54 minutes through Dani Alves.
Xavi managed to stab a pass into the path of the Brazilian full-back under pressure from a challenge and Alves coolly placed the ball past Iraizoz into the bottom far corner from seven yards.
The result looked far from certain as Athletic hit Barca on the counter at every opportunity in search of an equalizer.
An attacking substitution by Athletic coach Joaquin Caparros saw the arrival of Gaizka Toquero and his side deploy four in attack as they broke forward.
The tactic paid immediate dividends as Athletic sent the passionate home crowd into raptures by grabbing an equaliser on 63 minutes.
Fernando Llorente easily beat Dmytro Chygrynskiy in the air to a long ball played over the top of the and the six feet five inch striker flicked the ball on into the 18-yard box for Toquero to latch onto before curling the ball past the out-stretched arms of Valdes into the far corner.
Barca drove forward desperately in search of a winner that would send them back to the top of the table and Pique came close after attacking XaviÃ¢â‚¬â„¢s corner-kick, but his header cleared the crossbar by a matter of inches.
Xavi then came close himself on 83 minutes after seeing his shot from the edge of the box take a deflection and fizz just wide as Iraizoz scrambled low down to his right.
The goal, in truth, never looked like coming from then on and Athletic hung on to claim a deserved point.
Athletic Bilbao: Iraizoz, Iraola, Ustartiz, Amorebieta, Koikili, Guppegi, Orbaiz (Toquero, 57), Susueta, Javi Martinez, Yeste (Gabilondo, 74), Llorente (Oscar, 77)
Barcelona: Valdes, Dani Alves, Pique, Chygrynskiy, Maxwell, Busquets, Xavi (Henry, 84), Keita, Iniesta, Pedro, Messi (Bojan, 76)
Man of the Match: Xavi Ã¢â‚¬â€œ Orchestrated attacks from the heart of the midfield, including the goal, and came close himself on several occasions.
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