City's hopes of reaching the quarter-finals appear in ruins after the Spanish champions claimed a controversial 2-0 win at the Etihad Stadium.
Most of the post-match attention centred on City manager Manuel Pellegrini's reaction to the game's pivotal moment - when Martin Demichelis conceded a penalty and was sent off - and the Chilean's thoughts on Swedish referee Jonas Eriksson.
Pellegrini claimed Eriksson lacked control and was "on the side of Barcelona from the beginning until the end".
UEFA confirmed on Wednesday it is waiting for the delegated match official to file a report before deciding whether to open any proceedings against Pellegrini, which could lead to a warning, fine or even a touchline ban.
Few could deny that Barcelona, who had 68 per cent of possession, deserved their success overall. They were the more clinical side when it mattered and had City on the back foot for large spells.
City, however, can take comfort from the fact that they did limit the Catalans' chances and created a few openings themselves.
They may face a daunting task to turn the tie around in the Nou Camp next month but the feeling in the dressing room is that the cause is not lost.
Defender Pablo Zabaleta said: "Nothing is impossible in football.
"We still have 90 minutes to try to do something. We should go there and try as hard as we can.
"I think we must be happy with what we did in the second half with 10 men.
"Maybe Barcelona had more possession but they didn't create too many chances because we were very solid defending.
"Also we had chances to score and (Barcelona goalkeeper Victor) Valdes made a few saves.
"At the end of the day we must be a little bit disappointed but now we need to have belief and try to do well in Camp Nou."
Playmaker Samir Nasri hopes City can produce a response similar to the one they mustered after being humbled by Bayern Munich in October.
City were outplayed as they lost their home group match to the reigning champions 3-1 but they won the return match in Germany in December 3-2.
Nasri said: "It is a different game but why not? We went to Munich and we won. We could do the same.
"I think it is not over. It was a close game and then the referee made a mistake.
"It was not a pen, it was a free-kick. We still have a chance and we are going to play the game there without fear and try to score as soon as possible."
City spent most of the first half soaking up Barcelona pressure but had good chances when Alvaro Negredo shot across goal and glanced a header wide.
Barcelona upped the tempo after the break and broke through when Lionel Messi raced onto an Andres Iniesta through ball and was brought down by Demichelis.
The straight red card shown by Swedish official Jonas Eriksson was not contested but City - and notably Pellegrini - felt contact was outside the box and Jesus Navas had been fouled in the build-up.
Messi tucked away the spot-kick and - although David Silva went close to an equaliser - Barcelona were unlucky to have a Gerard Pique goal ruled out before Daniel Alves grabbed their second in the last minute.
City midfielder Fernandinho said: "It is very disappointing, because the decision of the referee was very important for this game.
"It changed the result, it changed the performance of both teams.
"Of course you have to go there with confidence. I am sure our players and the staff will prepare very good for this game.
"We will go there and try to beat them to go to the next stage."
Barcelona defender Javier Mascherano also feels City cannot be written off.
The former Liverpool player said: "It is a good result, but nothing is made. We have to play another game and it will be difficult.
"We know how strong Man City are, we know they can score any time and probably (Sergio) Aguero will come back.
"To go through to the quarter-finals we have to play with the same mentality we did here."