A drab opening period brought no goals for either side, but Atletico did look the more likely to open the scoring.
Diego Costa made an immediate impact for the home side, however, as he scored just past the hour mark, little under five minutes after entering the field.
Both teams had chances in the latter stages, but neither could add to the scoring as Atletico continued their sensational home record.
Read how it all unfolded in Sports Mole's minute-by-minute live commentary of the action below.
ATLETICO: Courtois; Juanfran, Miranda, Godin, Cisma; Gabi, Suarez, Koke, Turan; Adrian, Falcao
BETIS: Adrian; Perquis, Nacho, Chica, Amaya; Benat, Canas, Perez, Castro; Pabon, Campbell