Messi injury blights record start for Barcelona
Barcelona's Chiliean forward Alexis Sanchez (L) vies with Almeria's defender Angel Trujillo in Almeria on September 28, 2013.
Messi had fired the visitors into a 21st-minute lead with a sensational piece of play as he cut inside two defenders before curling the ball in off the far post from 20 yards.
However, the Argentine had to be replaced six minutes later due to a hamstring problem that puts his participation in Barca's Champions League trip to Celtic on Tuesday in doubt.
Messi will undergo tests on Sunday to discover the exact extent of the injury.
Despite looking far from their fluent best without the World Player of the Year, Barca doubled their advantage when Adriano prodded home Cesc Fabregas' cross early in the second-half and comfortably saw the game out.
"Leo apparently has a muscular problem in his right leg which he suffered when scoring the goal. More than that, it is difficult to say until they do the tests," said Barca boss Gerardo Martino.
The champions have now won their first seven league games for the first time in their history and 12 league games in a row stretching back to the end of last season.
However, Martino was quick to give the credit for the record-breaking start under his tutelage to the players.
"These boys have broken many indivudual and collective records over the past few years before I got here," he said.
The Argentine was though happy with how his side controlled the game in the second period after a shaky spell following Messi's withdrawal.
"We were a bit imprecise in the first-half, we gave the ball away a lot which allowed Almeria to counter-attack.
"In the second-half we had complete control. Especially after Adriano scored the second goal we could relax and with Xavi, Andres (Iniesta), Cesc and (Sergio) Busquets we moved the ball very well in midfield."
Martino continued with his policy of rotating his star names with Xavi and Neymar starting on the bench, but Barca still started the game strongly.
Iniesta forced Esteban into a fine save after just six minutes with a left-footed volley form outside the area before Gerard Pique ought to have opened the scoring when he failed to properly connect with Messi's free-kick at the back post seven minutes later.
Messi did then give Barca the lead with a sweet strike from the edge of the area to register his 11th goal of the season.
He was clearly in some discomfort thereafter though and was replaced by Xavi Hernandez.
The withdrawal of Messi understandably gave Almeria a huge boost and they finished the opening period the stronger.
However, Rodri's volley that Victor Valdes comfortably parried to safety was as close as they came to an equaliser.
Barca were more composed at the start of the second period and made the game safe 10 minutes after the restart when Fabregas' low cross was turned home from close range by Adriano for his second goal of the campaign.