Atletico Madrid president Enrique Cerezo has said that he is "optimistic" about the club's chances of signing Diego Costa from Chelsea.

Atletico are currently serving a transfer ban which prevents them from registering any new players until January, but they are understood to have made a breakthrough in their discussion to bring Costa back to the club in a reported £41m deal.

The Spain international is currently on strike at Chelsea, refusing to report for training and instead staying in Brazil after being informed via text during the summer that he no longer has a future at Stamford Bridge.

Any deal is likely to see Costa move on loan to a different club until January when he would be able to join Atletico, with the likes of Everton, AS Monaco, Marseille and Las Palmas linked with the striker in the meantime.

"[Costa] has a contract with another club, it's a complicated matter," Cerezo told reporters.

"We are taking things with ease. As long as Chelsea do not agree to his transfer, Costa will be [a] Chelsea [player]. Am I pessimistic or optimistic regarding the arrival of Costa? I am always optimistic."

Spanish clubs have until midnight on Friday to complete any deals, with their deadline being more than 24 hours later than the Premier League's.