Marca says Costa has asked the club to terminate his contact for personal reasons.
The ball is now in the club's court, and they will sit down to talk to the forward about the possibility of letting him leave in the winter transfer window.
Diego Costa's contract ends in 2021, but he has been a key player for Diego Simeone at the club, particularly during his first spell. If he doesn't change his mind, Los Rojiblancos will try to facilitate his departure by finding an agreement that suits all parties.
The Spain forward hasn't enjoyed the same form since returning from Chelsea, and he has been hampered by a number of injury setbacks in his second spell.
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