Bayer Leverkusen have enquired about taking Malang Sarr on loan from Chelsea as part of a big-money deal for Kai Havertz.
The 21-year-old centre-back recently joined Chelsea from Nice but could be sent straight out on loan as a makeweight in the move to sign Havertz.
The two clubs are moving closer to completing a deal for Germany international Havertz, which would be worth up to £90m.
The winger is ready to sign a five-year contract and has made it clear he wants to join the Blues.
Havertz is currently with the Germany squad preparing for their Uefa Nations League matches against Spain and Switzerland.