Chelsea want to snap up the shot-stopper, with Frank Lampard a fan of Mendy and keen to have him between the sticks at Stamford Bridge for the new season.
It had been claimed that a deal to take Mendy to Chelsea has been done, but according to French magazine France Football, there is no agreement in place.
Rennes have not yet agreed to sell Mendy to Chelsea and are looking for more money from the Blues.
The two sides are negotiating and Rennes want to earn €30m from selling the 28-year-old.
Mendy still has another three years left on his contract at Rennes, but is keen to make the move to Chelsea.
The goalkeeper will not be involved against Nimes on Sunday, with Rennes claiming a small physical issue will keep him from playing.
Mendy last played for Rennes on 22nd August as the club played out a 1-1 draw against Lille, and it remains to be seen if that will eventually prove to be his last outing.