Chelsea are understood to have rejected a £30m offer from Manchester City for David Luiz.
Sky Blues boss Roberto Mancini is keen to boost his defence after Micah Richards was ruled out for 10 weeks through injury, The Sun reports.
Speculation surrounding Luiz's future emerged when the Brazilian defender was left out of the Chelsea side that defeated Reading 4-2 last night.
Luiz later clarified over Twitter that he is suffering from a knee injury - a move which saw him fined by the club.
Chelsea manager Roberto Di Matteo said: "This social media thing is all around us now. We'll deal with it internally."
Luiz joined Chelsea from Portuguese club Benfica in 2011 in a deal worth £21m.
