Atletico Madrid are in advanced talks to sign Chelsea striker Alvaro Morata, according to Sky sources.
Chelsea would prefer a permanent deal, with the club eager to recoup as much of their investment back as possible, having signed Morata for a club-record £70m from Real Madrid less than two years ago. They value him at £45m.
Morata wants to return to Madrid, but the deal hinges on whether Chelsea can bring in a replacement. It is understood Chelsea are increasingly confident they will sign Gonzalo Higuain on loan with an option to buy.
The Spain international was not even on the substitutes' bench for Chelsea's 2-1 win over Newcastle on Saturday and was pictured in Madrid on Monday.
He has been linked with a Stamford Bridge exit after losing his place as Chelsea's first-choice striker, with Sarri preferring to utilise Eden Hazard as his main point of reference in attack.
Morata has been linked with both Sevilla and Barcelona in recent weeks but Atletico - the club where he began his youth career - now look like frontrunners for his signature.
Chelsea sold Diego Costa back to Atletico just three months after signing Morata.
But Costa has struggled to stay fit this season and has scored just one goal in 11 La Liga matches, prompting Atletico to look for another attacking option to complement Antoine Griezmann.