Lionel Messi was Barcelona's goal maker as the four-time champion dominated in its Group G Champions League victory Tuesday.
Messi created chances for Alexis Sanchez to score in the sixth minute and Cesc Fabregas in the 55th for a 2-0 win away to Benfica.
Barcelona's comfortable night was tarnished late on as the four-time champion lost captain Carles Puyol who dislocated his left elbow after landing awkwardly. Midfielder Sergio Busquets was then shown a straight red card for lunging into challenges too aggressively.
Bayern Munich, the beaten finalist last season, lost 3-1 to BATE Borisov in Belarus, Valencia beat Lille 2-0 and Braga won 2-0 at Galatasaray.
In the early kickoff in Barcelona's group, Celtic scored a 90th-minute goal to win 3-2 at Spartak Moscow which led in the second half before having defender Juan Manuel Insaurralde sent off.
Messi has started the season in sparkling form in Spain, and the Argentina forward was a creative force at the Stadium of Light in Lisbon.
The Argentina forward hit a fierce low cross from the left that Sanchez poked in from close range, and was denied by a smart low save by Benfica goalkeeper Artur in the 22nd.
Messi helped ensure victory when, after luring a group of defenders toward him, he laid off a pass to Fabregas in space to fire a left-foot shot into the net.
Puyol was carried off on a stretcher when he falling heavily on his left arm after leaping to meet a corner in the Benfica penalty area in the 75th.
Barcelona leads Group G with six points, two clear of Celtic which it plays next in Spain in three weeks' time.
Celtic led in the first half through Gary Hooper, but fell behind to two goals from Spartak's Nigerian forward Emmanuel Emenike. With a player advantage, the Scottish champion leveled with an own goal by Dmitry Kombarov then won through a Georgios Samaras header.
"They were magnificent and they played magnificent football at a very tough venue against an excellent side," Celtic manager Neil Lennon said.
BATE stunned Bayern to take control of Group F with its second straight 3-1 win, after beating Lille last month.
The Belarus champion scored through Aleksandr Pavlov in the 23rd minute and Vitali Rodionov netted the second in the 78th. Bayern got a stoppage-time goal from Franck Ribery but Renan Bressan then sealed the win.
"We always believed that we could win this match," BATE forward Aleksandr Hleb said. "We were confident even after we conceded the late goal."
Valencia's Jonas scored in each half Jonas against Lille, which had defender Mathieu Debuchy sent off.
Information from The Associated Press was used in this report.