The striker, 28, last played for Chelsea in the FA Cup final in May, and was sent a text in June by boss Antonio Conte telling him he would not be part of the squad for next season. Costa says the club are now demanding he return to train with the reserves.

"Why won't they let me go if they don't want me?" he told the Daily Mail.

"I have to do what I have to do. I have to think of myself. I've been a good boy here and tried to do the right thing. My desire is to go to Atletico.