The City boss was dismissed at half-time at the Etihad on Tuesday night for remonstrating with Spanish referee Antonio Mateu Lahoz after he disallowed Leroy Sane's legitimate effort for offside.
And manager Pep Guardiola says the Argentina forward could not train after that incident, but pushed himself in an unsuccessful attempt to rescue City's European campaign in the final 24 minutes of the second leg against Liverpool.
"I don't know. We can not forget he was one month injured". I am a human being and I have a passion.
"I accept I may not be starting but I would expect to be getting on for 35 or 30 minutes, I am the all-time leading goalscorer at this club".
"I said after the game congratulations to Liverpool", Guardiola said.
"I think Sergio probably feels a bit disrespected having scored all the goals he has scored". We saw how good we were doing - 2-0 is completely different. We handled the pressure between the good and bad moments for the entire season, not just in this period.
"I will definitely be better but I am who I am".
He said: "I prefer to be with my players than my chairman but it's the decision of the referee".
Five congresspeople and Senator Warren finally object to Israel shooting unarmed Palestinians
People attend a protest against the killing of a fellow journalist Palestinian Yasser Murtaja on April 11, 2018 in Istanbl. The Palestine Red Crescent Society, a humanitarian organisation, has said one of its medics was shot in the knee.
It's been a tough last couple of weeks for Guardiola and City, three defeats in the space of eight days at the hands of Liverpool on two occasions either side of a Derby Day loss has seen them exit the Champions League and has put their title celebrations on hold.
Pep Guardiola has cast doubt over Sergio Agüero playing for Manchester City again this season. "Hopefully (he will be back) for the last games, if we need him, and especially for the World Cup". But in one week we lost three games, that happened. That's why he could not play from the beginning. People talked about it but he was not ready.
"Fernandinho is suspended, John Stones is not ready, (Benjamin) Mendy is out". It is what it is. There are six games and 18 points left to play for this term, while second-placed United trail City by 13 points. The players know that, it's not necessary to tell them. I'm sad, we all are sad.
"They [the players] know that". They can even afford for City to win one and draw one, presuming that Jose Mourinho's men are prepared to win all six of their remaining games.
"All the other contenders, after losing a game, have maybe lost another one - and we didn't do that". All teams lose games.
But despite needing only five points to be certain of his first Premier League title, Guardiola says his side can still be caught. Tottenham is what it is. We have to win two and [against Spurs] we're going to start to do it the way we do it.
'We must try to be who we were during the season.
'But Tottenham are fantastic.