Kai Havertz's first half strike earned Chelsea a 1-0 win out in Porto and condemned City to defeat.
Aguero is leaving as the club's all-time top scorer - but brother Mauricio del Castillo believes Guardiola wanted to end his Etihad career even sooner.
In a now-deleted rant on Twitter, he said per Mirror: "Guardiola never wanted my brother since his arrival at City."
so aguero's brother tweeted yesterday after the game : "guardiola has never liked aguero" (tweet's been deleted since).- (@ElMariomutsch) May 30, 2021
So he was indeed acting once more when he fake cried https://t.co/qmWiwbpP5u
That initial tweet was then removed and when asked why, he replied: "Many toxic people, too many."
The 25-year-old, who is also a striker and plays for Independiente, replied: "Perfect, I'm glad people have seen it and I'll write it again if I want."
Gabriel Jesus was signed in 2017 by Guardiola and many believed it was a direct replacement for Aguero.
However, he ended up sticking around an additional four years and remained their main man up front.
Guardiola was also visibly emotional when discussing his departure earlier this month, following their final Premier League game of the season.
He told Sky Sports through tears: "He's a special person for all of us.
"He's so nice. He helped me a lot, he's so good. We cannot replace him, we cannot.
"There have been many players at this club, like Joe Hart and David Silva, who have helped us to be this club -- what it is.
"We helped his legacy and he showed his quality in 20 minutes."
Aguero, who is expected to join Barcelona on a free transfer, has also been described as 'irreplaceable' by his former manager.
"Sergio is irreplaceable," the Spaniard added. "I could say in terms of numbers he could be replaceable but it's not easy. When you see around 360 games and more than 250 goals, the amount of titles.
"He's a legend, the best striker I ever had at this club... but he's irreplaceable in the mind for our fans, to our people and to the players that played alongside him or the manager who worked with him.
"A fantastic person and human being. I think if his mind is still aggressive like he is, he can stand his career longer for two, three, four or five years.
"When I took over the club, he was one of the guys who helped. Not just him - we had Joe Hart, Pablo [Zabaleta], Vincent [Kompany] and David [Silva].
"Many, many players helped this team to take a step forward and of course he was one of them.
"When he came here the club was at one level and he helped put the club at a higher level and that's why all the people and the fans are grateful."
Featured Image Credit: PA Images
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