The midfielder has signed for the Stamford Bridge club on deadline day, sealing a loan agreement.
Chelsea have the option to buy Saul for roughly £30 million at any stage of the agreement.
"Saul was not very satisfied in the position [wing back] in which he was playing and has decided to leave," Cerezo said, per the Daily Express.
"Wherever he goes he will be a great player and much loved by Atletico de Madrid."
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