With three of the top four sides - Santa Fe, Atletico Nacional and Boyaca Chico - not in action due to delays created by clashing Copa Libertadores fixtures, Once Caldas missed the chance to go top on Wednesday as they were beaten 2-1 away at Envigado.
Oscar Rodas scored a brace for Envigado, with his second goal coming in the 83rd minute - moments after team-mate Yilmar Angulo was red carded.
Once Caldas will be rueing their inability to take something from the match as a point could have put them level with pacesetters Santa Fe.
Instead, Caldas are one of five teams on 15 points, including Junior and La Equidad.
Junior were humbled 1-0 away at Alianza Petrolera on Thursday, after both sides had seen a man sent off.
Alianza had Jonathan Avila red carded in the first minute after the half-time interval, only for Juan Dominguez to square the ledger at 10 men each when he was dismissed on 72 minutes.
Ayron Del Valle then scored the winner for the home side, netting in the 87th minute to give Alianza their first win of the campaign to take them off bottom spot.
La Equidad were held to a 1-1 draw at home to Deportivo Pasto, with the visitors scoring in the final 11 minutes via Bosco Frontan.
Deportivo Cali are the only remaining winless side in the league after Alianza's success, and fell to a 3-2 home defeat to Itagui.
Cali were on top early, leading 1-0 in the shadows of half-time before goalscorer Robin Ramirez was red carded.
Itagui pounced on their man advantage, scoring three goals in a 22-minute period to bury Cali - two of which came via Cleider Alzate.
Sergio Romero scored for Cali with 15 minutes to play to give them hope of a revival, but they could not add to their two points tallied this season.
In other results, Uniautonoma had a 2-0 win at home over Patriotas Boyaca, Millonarios and Atletico Huila drew 2-2, and Medellin and Fortaleza played out a six-goal thriller 3-3.
