The News of the World says new Blues chief executive Ron Gourlay found out the £30million-rated striker earns £4m a year NET.
Blues thought their No 1 target made around £50,000 a week but it has now emerged he earns more than double that.
Aguero, has been told he can leave Atletico in the January transfer window. But he has already made it clear he will not settle for a penny less if he moves to Stamford Bridge.
His wage demands have stunned Gourlay, who is hoping to make Aguero his first signing since replacing Peter Kenyon.
And that's before shelling out the £30 million Atletico will demand for the Argie's sale.