Alvaro Morata arrived at Stamford Bridge at the beginning of last season and has since been struggling to find his form.
Atletico Madrid wants to sign Morata and have already started talks with Chelsea, reports claim.
The 26-year-old was spotted in Spain on Sunday night and a permanent transfer to Diego Smeone’s side is closer.
He has just five Premier League goals this season but has been left out in recent weeks.
The Spaniard has played just two of the last seven league matches and was not even in the matchday squad for the other five, including on Saturday against Newcastle.