Lionel Messi scored a hat-trick as Barcelona punished 10-man Manchester City in the Champions League on Pep Guardiola's return to his old club. City were competitive in the first half, but made far too many errors against a ruthless Barcelona revelling in Messi's return from injury. A Fernandinho slip inside his own box put Messi clear for his first, then Kevin de Bruyne lost possession allowing Andres Iniesta to set up the Argentine for a left-footed strike into the bottom corner. The victory maintained Barcelona's 100% start in Group C and extended their lead over City to five points.