Corinthians president Andres Sanchez says if the deal is not agreed by Sunday the move will not happen, with the transfer window in Brazil set to close on July 20.
"I was in Argentina for a Brazil match [at the Copa America], I spoke with Tevez and his representative on the phone," Sanchez told Lancenet.
"Corinthians have made an offer of approximately 40million [£35 million] to sign him permanently. This sum means we will be spending 20 to 25 per cent of our TV rights earnings if City accept it.
"I have made an offer which I think City cannot refuse, and we will not raise it further. If they ask for [£50 million], they will keep him.
"If we haven't closed the deal by Sunday it won't happen this year."