Edouard Mendy is having his medical at Chelsea after the club agreed a £22m fee with Rennes for the goalkeeper.
The deal is expected to be completed in the next 24 hours following his medical and finalising personal terms.
Pressure has increased on Frank Lampard to bring in a new goalkeeper following two mistakes from Kepa Arrizabalaga from their opening two Premier League matches.
Chelsea have been in talks with Rennes since before the start of the season over the possibility of bringing Mendy to the club.
Lille’s Mike Maignan was also on Chelsea’s list of goalkeeper options but a price tag of £32m put Chelsea off.
Petr Cech, Chelsea’s technical director, has strong links with Rennes and has been involved in identifying Mendy as a target.
The 28-year-old kept nine clean sheets in 24 Ligue 1 appearances last season.
Mendy will become Lampard’s seventh first-team summer addition, joining Timo Werner, Hakim Ziyech, Ben Chilwell, Thiago Silva, Malang Sarr and Kai Kavertz.
Bosnich: It’s not the end for Kepa
Mark Bosnich says it is right for Chelsea to bring in competition for Kepa Arrizabalaga after he has started the season with two high-profile mistakes.
The former Chelsea and Manchester United goalkeeper, though, doesn’t believe it is the end for the Spaniard and thinks the competition could help him.
Bosnich said: “I don’t think it’s the end. But it’s been quite obvious for some time that Frank Lampard and his staff aren’t over the moon about him, we saw that last season.
“He needs competition. All big clubs should have competition in every position, including goalkeeper.”
Summer transfer window – key dates and times
The summer transfer window will run for 10 weeks from July 27 and close at 11pm on October 5.
A domestic-only window for trades between the Premier League and EFL then runs from October 5 and closes on Friday, October 16 at 5pm.