A hard-fought first half gave way to a more entertaining second as Barcelona deservedly - but with difficulty - took all three points home with them from the Basque country.
First Half
Barcelona came out with a mission, but Athletic, lining up 4-5-1, had one of their own: preventing slick, open football from the visitors.
The home side were pressing avidly from the first minute and after winning possession early on gained a free kick 25 yards out. It was up to Víctor Valdés to pull off an acrobatic save from David López's set-piece effort.
Still, Barça had some tricks of their own, and Eto'o had the beating of Amorebieta up front, so it was not too surprising when the Cameroonian forced a stop from Gorka Iraizoz at the other end.
Nonetheless the match was characterised by scrappy midfield play and long shots in these early stages as neither side could quite establish a rhythm. Iniesta shot over at one end, while the vastly-improved Valdés at the other pulled off another great dead-ball stop, this time from Yeste.
Barça were troubled by an injury to Keita on the half hour mark, necessitating the introduction of Busquets alongside his fellow cantera lad, Víctor Sánchez, and as such it took a few more minutes for the blaugrana to re-adjust.
In fact there were to be no more opportunities of note before the half-time whistle.
Second Half
After the break things were more to the neutral observer's liking as the game started to open up. Three minutes after the restart some fine work down the right eventually saw Iniesta cut the ball back for the onrushing Sánchez, but the youngster blasted his unmarked effort way, way over the ba.
Iniesta, in fact, had taken control of the game by this time, even allowing for Athletic's counters, but it was Henry who set up Eto'o for the opener.
The Frenchman's little through ball found Eto'o on the edge of the box, and so well timed was it that the striker was able to tip the ball past the flailing Amorebieta and go through on goal. The best was still to come, though, as Eto'os thunderous finish with his left foot left Iraizoz utterly helpless.
The hapless Amorebieta almost put through his own net minutes later with a header, but Iraizoz's diving save kept the score at 0-1 as the closing stage of the match began.
Markel Susaeta looked to spearhead the counters for Athletic, but Barça were wise enough at the back to deal with most of the hosts' threats on the break.
In fact Barcelona managed a counter of their own as they sat back towards the end, a swift team move eventually seeing Iniesta square the ball across for Eto'o only for the Cameroonian to roll the shot wide, much to his disgust.
As the clock wore down - and two Barça players were booked for aiding it in doing so - the three points headed back to Catalunya.
ATHLETIC CLUB BILBAO 0-0 FC BARCELONA
Athletic: Gorka Iraizoz; Iraola, Aitor Ocio, Amorebieta, Balenziaga; Orbaiz (Gurpegi 76'), Yeste; David López, Garmendia (Susaeta 60'), Gabilondo (Ion Vélez 75'); Llorente.
Barcelona: Víctor Valdés; Dani Alves, Márquez (Puyol 65'), Piqué, Abidal; Víctor Sánchez, Yaya Touré, Keita (Busquets 32); Iniesta, Eto'o, Henry (Hleb 79').
Yellow Cards: Amorebieta 38', Garmendia 48', Balenziaga 74' - Márquez 49', Busquets 88', Eto'o 89'
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