Knockout-phase debutants City matched Barcelona in the first half at the Etihad Stadium, but the game changed early in the second period when Martin Demichelis was sent off following a last-man foul on Messi.
The Argentinian international scored from
the ensuing penalty in the 54th minute, taking his tally of goals in
this season's competition to seven.
Despite
being a man down, City continued to threaten, but in the final minute
Alves ran through to score, leaving Barcelona firmly in the driving seat
ahead of the return leg on March 12.
Barça goalkeeper
Valdes was then given a moment of discomfort when Vincent Kompany got
his head to a free-kick from Silva, sparking a goalmouth scramble that
was cut short when Negredo was penalised for an infringement.
Negredo hit a snapshot straight at Valdes, before Barça came to life, with Messi firing over from the edge of the box and Xavi extending City goalkeeper Joe Hart with a rasping 25-yard drive.
The offence occurred right on the edge of the box, but referee Jonas
Eriksson awarded a penalty and after Demichelis had trudged off, Messi
planted the spot-kick past Hart.
Alves teed up Xavi
to shoot over and then drilled narrowly wide after a one-two with
Alexis Sanchez as Barca threatened to twist the knife, while Neymar's
introduction seemed to presage further bad news for City.
Instead, the hosts continued to push, with Valdes plunging to his right to repel a volley from Silva in the 77th minute.
Barça had
the final say, however, with Alves gathering a pass from Neymar and
tucking the ball between Hart's legs in the final minute to further
tighten the Catalans' grip on the tie.
