Andrey Santos is expected to be recalled by Chelsea from his Nottingham Forest loan spell in January, but regulations will limit his next move.
Chelsea rate the 19-year-old midfielder highly and are disappointed he has played just seven minutes in the Premier League since moving to Forest, with his solitary start coming in the Carabao Cup.
The Blues can break the loan arrangement should Santos fail to reach a certain number of appearances by January.
But the two clubs also have a friendly working relationship, having discussed a swap deal involving Brennan Johnson and Trevoh Chalobah in the summer, and would work for a mutually beneficial solution should he pass the threshold of appearances.
Santos could return to Chelsea despite huge midfield competition from Moises Caicedo, Enzo Fernandez, Conor Gallagher, Romeo Lavia and Lesley Ugochukwu.
New FIFA regulations state clubs can only have seven players out overseas loans at one time and Chelsea have reached that number, limiting Santos's loan move options to within English football.
Porto are one club known to be interested in the one-cap Brazil international, but it is unclear whether there is currently any Premier League interest.
Chelsea could cancel one of their current overseas loans but may face financial penalties or clubs vetoing any decisions.
Winger Diego Moreira could be a prime candidate for having his loan cancelled, having played just 75 minutes for Lyon this season, but that would cost Chelsea their sizeable £2.5million loan fee.
There is disappointment that Romelu Lukaku, Hakim Ziyech, and Kepa Arrizabalaga took up three of the seven loan spots and were not permanently sold in the summer.
