Atletico Madrid president Enrique Cerezo insists re-signing Diego Costa could yet happen.
The Chelsea striker has complained this week that Atletico failed to sign him last summer.
But Cerezo said: "The return of Diego Costa? He who hopes despairs. We love all the great players who have played Atlético Madrid and want to come back. There are times when you can do it and others do not.
"No, we did not give up. There are things that are impossible. And the transfer of Diego Costa was impossible at that time. Because he belongs to a big club, Chelsea did not want to let him go and, before the closing of the window we had to sign another attacker."