Chelsea are seeking to buy a new goalkeeper.
With Kepa Arrizabalaga having left on-loan for Real Madrid, new signing Robert Sanchez is their only recognised senior No1.
Lucas Bergstrom, 20, was on the bench with senior backup Marcus Betinelli currently injured with an unspecified issue.
The Sun says co-owner Todd Boehly has made available 20m to sign cover for Sanchez.
USA international Gabriel Slonina was loaned out by Chelsea earlier this summer to KAS Eupen.