The Colombian top-flight leaders have seven wins and a draw from eight matches, after most recently silencing 10-man Medellin.
Atletico were fired to victory by first-half goals to Francisco Najera and Jefferson Duque, before John Hernandez was sent off after 62 minutes.
Millonarios slipped up for the second straight week, as they were held to a 0-0 draw by third-placed Santa Fe in an ideal result for Atletico - who have six- and seven-point buffers on the two sides respectively.
Patriotas Boyaca defeated Boyaca Chico 1-0 courtesy of an Amiviled Rivas goal on 25 minutes, while Chico were left to battle with 10 for the final quarter-hour after Julian Carabali was dismissed.
All three goals scored in Deportes Quindio's 2-1 win over Once Caldas happened four minutes apart, in an extraordinary exchange.
Quindio led on 50 minutes from a Jaime Barreiro goal, only to be pegged back within three minutes via Caldas' Oscar Rodas.
The rollercoaster did not stop there, though, as Roy Castillo restored the home side's lead, and the remainder of the contest went goalless to see Quindio to their first victory of the season.
La Equidad smashed Alianza Petrolera 4-0 to go seventh, although they finished with 10 men when Fernando Battiste was sent off late.
Junior and Cucuta Deportivo ended level at 1-1, while Envigado got the edge on Itagui 1-0 away and Deportes Tolima snuck past Atletico Huila 1-0.
Deportivo Cali stayed in fourth spot, after their 0-0 home draw against Deportivo Pasto.
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