Aguero, 29, looked set to depart from the Etihad last season after being warned striker Gabriel Jesus was the preferred attacking option under the management of Pep Guardiola.
However, the Argentine remained at the club and profited from the mid-season injury of the Brazilian, netting 30 goals in 39 games across all competitions.
It took his overall tally to 199 strikes for the Citizens in 292 games as he surpassed Eric Brook's record set in 1940.
However, reports surfacing in Spanish media claims Atletico Madrid made contact with Aguero's representatives over a sensational return to the club, as they look to prepare themselves of a possible departure of Antoine Griezmann to Barcelona.
Radio Marca suggested manager Diego Simeone wants the transfer sanctioned even if the France international remains at the Wanda Metropolitano - as he attempts to build a squad strong enough to compete for league honours next season.