Aguero has long pledged his loyalty to Atletico Madrid, who bought him from Independiente in 2006.
The 21-year-old Argentina international was strongly linked with a move to England in the summer.
Now rumours of renewed interest from Chelsea, with a view to a January switch, are again emerging.
Chelsea have their transfer ban hanging over them, but they remain confident that at the very least that will be suspended in time for them to make some moves in the January window.
Atletico confirmed they rejected big offers for Aguero in the summer, and the player himself was more than happy to remain.
But Atletico's poor start to the season could now see a re-think at the Vicente Calderon.
"Sergio to Chelsea in January? I don't know, it's a difficult question," Aguero's agent Jose Segui told Calciomercato.
"The only thing I can say is that I actually don't know anything.
"I don't expect any meeting with Atletico Madrid."