"He made a huge effort, because after the action from Ashley Young against United, with problems in the knee, he could not train".
He felt severe discomfort and claimed he "couldn't run" after a 23-minute substitute appearance in the Champions League against Liverpool three days later.
The Manchester City ace famously scored the title-winning goal deep in added time of the last game of the season in 2012, commonly known as the 'Agueroooooo!' moment due to Martin Tyler's memorable commentary.
Returning to full fitness in time for this summer's World Cup will now be Aguero's main concern, with the showpiece event in Russian Federation now just two months away.
"Recovering from an arthroscopy on my knee. Fully motivated to get back soon to the field", Aguero wrote on Twitter.
'We have scored great goals, played fantastic football and learned together under Pep, ' added the Argentina striker, who missed Saturday's victory for Pep Guardiola's side at Tottenham with a knee injury. Again, he was only able to appear as a second-half substitute.
"This season has been incredible and the football we've played has been the best I've been involved with while at the club".
The World Cup in Russian Federation starts in two months.
In his absence, Gabriel Jesus can be expected to lead the line for the remaining games, and there could even be a chance for England youth global Lukas Nmecha who has been on the fringes of the first team this season and made his debut against Leicester City in the Carabao Cup last December.