Martin Demichelis' red card proved pivotal as Barcelona beat Manchester City 2-0 to take control of their UEFA Champions League last-16 tie.
The visitors had the lion's share of possession in the first half, but failed to cause home goalkeeper Joe Hart too many problems.
City soaked up the pressure well and carved out a few opportunities of their own, but Demichelis' foul on Lionel Messi early in the second half represented a turning point.
The defender was dismissed for bringing his fellow Argentinian down after he had been played in by a sublime Andres Iniesta pass, and Messi duly stroked home the resulting spot-kick for his seventh goal in four Champions League outings this term.
Barca's control over proceedings inevitably grew with their numerical advantage, and Daniel Alves added a second in the closing moments from close range - dealing a huge blow to City's chances of progression.
Alvaro Negredo was City's only out-and-out striker as Manuel Pellegrini looked to bolster his midfield and counter Barcelona's considerable attacking threat, while Gerardo Martino opted for Cesc Fabregas in place of Pedro.
The hosts struggled to get a touch on the ball in the opening stages as their visitors stroked it around with ease but, despite the Spanish champions' early dominance, it was two of the home side's Iberian imports who carved out the first chance of the match - David Silva playing in Negredo, who failed to find the net from a tight angle.
For an encounter between two of the world's most technically gifted sides, the deadlock was almost broken in the scrappiest of fashion in the 25th minute, as Victor Valdes' failure to deal with a Silva free-kick sparked havoc in the Barca penalty area. The goalkeeper eventually got back to his feet to claim the loose ball.
Messi got his first sight of goal on the half-hour mark, but scooped a right-footed effort over the crossbar, before Xavi forced Joe Hart into a diving save with a speculative effort from 20 yards.
Negredo headed just wide of the target from a Jesus Navas cross on the stroke of half-time as the sides went in level at the break.
But City's hard work in the first half unravelled nine minutes into the second, as the referee ruled that Demichelis had brought down Messi just inside the area - a challenge that earned the City defender his marching orders.
Messi picked himself up to calmly knock the ball straight down the middle past Hart.
City brought on Joleon Lescott as the focus shifted towards damage limitation ahead of the second leg, but could have found themselves two down when Alves drove the ball just wide of the left-hand post.
Silva took the ball down on his chest superbly in the Barcelona area 15 minutes from time, but Valdes got down well to keep out his eventual strike, before Pique had a goal disallowed at the other end after Fabregas was deemed to be offside.
Alves then stormed into the box in the 90th minute to slot home a goal that puts Barca in the driving seat ahead of the second leg on home soil.
|Coach: M. Pellegrini|
for A. Kolarov 58'
for Jesús Navas 58'
for Negredo 74'
|Allardyce: We must improve|
|Campbell thrilled by Palace switch|
|Bojan drawn by Stoke style|
|Palace were wasteful, says Pulis|
|Van Gaal suits me - Cleverley|
|Newcastle stay perfect in NZ|
|Van Gaal prepared to wait for Strootman|
|West Brom overcome Sacramento|
|Colorado Rapids 3 Chivas USA 0: Hosts rise to third in the West|
|Gameiro brace adds to West Ham woes|
|Villas-Boas: Rodriguez best suited to no.10 role|
|Cazorla: I´m happy at Arsenal|
|Reina respects Liverpool contract|
|Lampard could move to Melbourne on loan|
|Galliani: Balotelli ´99.9 per cent´ staying|
|Own goal helps Palace win in Philadelphia|
|Mourinho: Shaw deal would have ´killed´ Chelsea|
|Al Ahli Benghazi 0 ES Setif 2: Visitors on verge of semi-final spot|
|Julio Cesar returns to QPR|
|Rooney wants to lead United|
|Lallana to miss up to six weeks with knee injury|
|Isgrove maintains Koeman´s perfect start|
|Lens announce Ligue 1 appeal success|
|Pekerman talks due in August|
|PSG sanction ´harsh´, claims FFF chief|
|Garcia: Strootman going nowhere|
|Van Aanholt departs Chelsea for Sunderland|
|Benfica sign Manchester United flop Bebe|
|Campbell makes Palace move|
|Reed signs new deal at Southampton|
|Juve stunned in Allegri´s first match|
|AFA fined over Falklands banner|
|Robinho likely to move, claims agent|
|Drogba completes Chelsea return|
|Kiyotake moves to Hannover|
|Marotta: Juventus eyeing striking additions|
|Bakayoko set for Monaco switch|
|J.League Preview: Vortis out to improve dismal fortunes against Ardija|
|Juve complete Pereyra deal|
|Ranieri named Greece head coach|
|Fiorentina agree Basanta deal|
|Di Natale backs Pereyra´s Juve move|
|Iniesta: Suarez has talent to restore Barca glory|
|Cerci in charge of his future, says Cairo|
|West Ham target new striker|
|Pardew hopeful over De Jong|
|Rodgers expects new Gerrard deal|
|Jones: United embracing Van Gaal methods|
|Henry: Time had come to sell Suarez|
|Brunt eyes new West Brom deal|
|Arsenal´s World Cup winners to miss league opener|
|Modric hails Rodriguez, Kroos signings|
|Cech does not want bench role|
|Inzaghi blames fatigue for Milan loss|
|Real´s time to shine, says Ancelotti|
|Real Salt Lake 3 Montreal Impact 1: Garcia stars in Utah|
|Downing: Carroll injury a ´big blow´|
|Irvine: I have not seen Ideye play live|
|Olympiacos triumph in Toronto|
|Giggs likens Van Gaal to Ferguson|
|Copa do Brasil Review: Corinthians among trio on the verge of progression|
|Blanc: World Cup stars will move on|
|Pinto steps down as Costa Rica coach|
|Mourinho planning Drogba swoop|
|UEFA Europa League Review: Rosenborg complete comeback to see off Sligo|
|Mathieu out to enjoy Barcelona move|
|Mandzukic not Diego Costa´s replacement|
|Eliseu returns to Portugal with Benfica|
|Sanabria makes Roma switch|
|Carroll to miss start of season|
|Vidal: I´m not going to Manchester|
|Xavi staying at Barcelona|
|Hannover complete Gulselam signing|
|Astori loaned to Roma, Cagliari confirm|
|Nigeria to talk with Keshi over return|
|Gamberini makes Chievo move|
|Besic poised to complete Everton move|
|Marseille move Montpellier fixture from Stade Velodrome|
|CSL Preview: Harbin eye Luneng scalp, Guangzhou face Hena|
|Guardiola preaches patience with Lewandowski|
|Lampard joins New York City|
|Blanc coy on Di Maria speculation|
|CAF Confederation Cup Preview: ASEC coach confident, Al Ahly seek qualification|
|Chelsea loan Piazon to Frankfurt|
|Pochettino has high hopes for Lamela|
|Aguirre appointed as Japan coach|
|Swansea swoop for Montero|
|Pozuelo makes Vallecano switch|
|Fred back at Shakhtar, Ismaily to follow|
|CFF investigate Fofana accusations|
|Suarez could make sensational Clasico debut|
|Ribery in line for return, says Guardiola|
|Reus could resume training in two or three weeks - Klopp|
|Roma need another defender, says Garcia|
|Everton on verge of new signings|
|Rodrigo hails Nuno after Valencia switch|
|Delph eager for new Villa deal|
|Ljajic not seeking Roma exit|
|Talks held as players strike in Ecuador|
|Crouch excited by Bojan capture|
|Lambert expects swift recovery for Cole|
|West Ham duo fail to travel|
|United to play 3-4-3, says Van Gaal|
|Lallana, Markovic set to feature against Olympiacos|
|Real want to win every trophy, says Bale|
|San Jose Earthquakes 5 Chicago Fire 1: Hosts break winless streak|
|Chelsea have "outstanding squad" - Costa|
|United make winning start under Van Gaal|
|Rodgers plays down Borini injury concerns|
|Atletico Mineiro 4 Lanus 3 (agg 5-3): Own goals gift Brazilians the win|
|Dunga names Brazil assistants|
|Man City show class in Kansas|
|Villa too good for Dallas|
|Santos cannot meet Robinho´s demands, says vice-president|
|Mourinho happy with goalkeeper situation|
|Borini hurt as Liverpool lose to Roma|
|Palace held to draw by Crew|
|Tottenham down Toronto after Lamela brace|
|San Lorenzo 5 Bolivar 0: Hosts close in on Copa Libertadores final|
|Sunderland forward Scocco joins Newell´s|
|Rodgers: We won´t overpay in transfer market|
|Maccabi Haifa friendly abandoned after pitch invasion|
|USA dynamo Beasley joins Houston|