The Slovenian custodian has conceded only 18 goals in the Spanish top flight this term, the lowest amount since Deportivo La Coruna shot-stopper Paco Liano also let in 18 strikes in 1993-94.
Oblak has been ever-present for Atletico this season, starting all 38 of Diego Simeone's side's league encounters.
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Despite their fantastic defensive record, the capital club were unable to win the La Liga title, instead finishing third behind runners-up Real Madrid and champions Barcelona.
But Oblak can at least take solace from his excellent achievement, with Liano no longer the sole holder of the record.