The Spaniard signed for the Blues months after they secured their maiden victory in Europe's elite competition via a penalty shoot-out win over Bayern Munich in 2012.
During a nine-year stint at Stamford Bridge, the defender has won two Premier League titles, one FA Cup, one League Cup and also been victorious in the Europa League twice.
"We tried our luck, we did not make it. He decided to stay in Spain, move to Atletico and has proven his quality.
"He is a natural striker, a born striker, and has the certain mentality that only strikers have. This mentality is to show his will, intensity and anger to score, score and score. He is never satisfied, so what a mentality and what a player.
"I'm not involved in his history with Chelsea and to me it's never good to look too far in the past. We only look forward.
"We play him tomorrow with Atletico and we know about his qualities. We are aware of them and will try to stop him from scoring."