Guardiola felt City were on the wrong end of some poor decisions, which he felt included Raheem Sterling being denied a penalty after a challenge by Andy Robertson. This has more to do with the vanity of the commentators than the reality on the pitch.
His mood wouldn't have improved 12 minutes into the second half, when Liverpool nicked the crucial away goal.
It proved costly for Barcelona.
The Reds ended City's hopes of adding European silverware to their all but certain English top-flight title and have now won three successive fixtures between the sides this term.
City recovered to win that game 5-3 but lost the tie. They overhauled City's youth system and constructed new training facilities with Guardiola in mind.
Georginio Wijnaldum was deployed in a somewhat unfamiliar defensive-midfield role to cover the absence of the suspended Jordan Henderson, and was a key part of Liverpool securing victory as he was able to break up the play and get his side back on the front foot.
Asked why he was sent off after confronting the referee, Guardiola replied: "I said it [Sane's effort] was a goal".More news: Zuckerberg addresses rumours about Facebook tapping your microphone
Kostas Manolas' header sealed Roma's first trip to the European Cup semifinals since 1984. Instead of 2-0 at the half, we went in with a slim lead, and no manager on the sidelines. "That's quite a big thing".
Defending, of course, has been a major issue with City recently, with eight goals conceded in six days.
Credit where it's due, City's players have been gracious in defeat and now Benjamin Mendy has jumped on the bandwagon by sending a classy tweet to Liverpool. You need to react in the right way. It's all about going to the next round - that's what we will try to do tomorrow.
Klopp says his side are still a work in progress. Guardiola will look at his team, and those left in the competition, and think 'it was there for the taking'.
Changing City's attitude towards the Champions League is no longer their overriding problem.
"It would have been different to go in 2-0".
"I'm on cloud nine", Pallotta said at the Stadio Olimpico. That doesn't make us the better team, but it's football. We got about them a bit more second half, but we defended well again and that's the key'.
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