The 21-year-old, who won Spain's "Zamora" trophy for conceding the fewest goals in the top flight last season, said on Atletico's website he had wanted to stay on to compete with the Spanish side in the Champions League next term.
He has made 98 appearances for Atletico, helping them win the Europa League in 2012, the European Super Cup, when they beat Chelsea in the final, and last season's King's Cup.
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