This was a fine tactical plan from Manuel Pellegrini, undermined by a single error from Martín Demichelis
Barcelona were unquestionably the dominant side but this defeat will be particularly frustrating for Manuel Pellegrini after his defensive game plan worked effectively for long periods. Pellegrini was cautious up front, using only one forward, and he played two full-backs in tandem to nullify Daniel Alves. However, he did not field a true holding midfielder and, with Yaya Touré and Fernandinho battling against Xavi Hernández and Cesc Fábregas in the early stages, Manchester City's defenders received little help in trying to stop Lionel Messi.
This did not prove problematic, however. City replicated their strategy from the 2-0 win over Chelsea on Saturday, with the defenders being extremely aggressive in their positioning. Gaël Clichy practically man-marked Alexis Sánchez while Pablo Zabaleta tracked Andrés Iniesta, before passing him on to Vincent Kompany when the playmaker drifted centrally.
Then, there was Martín Demichelis against Messi – and, surprisingly, the defender actually coped well in the first half. He played proactively, anticipating passes into Messi's feet and charging forward to make interceptions. His distribution was poor, but the fundamentals of his defensive play were sound.
Barcelona's caution in possession made City's life reasonably easy and the lack of purposeful, off-the-ball running was astounding. Sánchez was the only threat in behind, with Messi and Iniesta moving towards the ball, plus Fábregas and the full-backs playing cautiously, to guard against counter-attacks.
City coped when able to defend deep but were exposed by a move completely uncharacteristic of Barcelona's approach. There was no build-up to the penalty decision – Barça won the ball, then immediately played the killer pass.
Messi was dawdling in an offside position after a Barcelona move had broken down and his clever positioning made it almost impossible for City to stop him. He waited until City's centre-backs had retreated, playing him onside, then Iniesta instantly played the through-ball. While Demichelis had no problems in the first half when moving higher up the pitch, turning and sprinting was an entirely different matter – his challenge was clumsy and the dual punishment of a red card and a penalty completely changed the tie.
Barcelona dominated with a one-man advantage. But Pellegrini moved to a 4-4-1 and City had some decent moments when their full-backs advanced: Clichy overlapped before crossing poorly, while Touré switched play for Zabaleta's knock-down, and David Silva's fine effort.
However, after Pellegrini understandably removed Aleksandar Kolarov to introduce more creativity, Alves was rampant: shooting narrowly past the far post and setting up Xavi for a decent chance, before doubling Barcelona's lead in the final minute. Even Alves's influence, though, justified Pellegrini's decision to start with Kolarov. This was a fine tactical plan from the Chilean, undermined by a single error.