City have rejected Corinthians' initial bid of ?35million for the Argentina international, with the Premier League outfit thought to be holding out for a ?50million transfer fee.
Sanchez admits that, if a 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 euros (?35million) 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."
Tevez admits he would have no problem returning to Corinthians after two successful years in Brazil prior to his move to England with West Ham in 2006.
"An offer arrived and I would have no problem returning," said Tevez.
"They got in contact with me, sent an offer to the club and in eight to 10 days, the transfer market in Brazil closes."
Source: Team Talk
Source: Team Talk