German Cano, Yulian Mejia and Marcos Perez all scored in the second half for Medellin on Sunday as they maintained eighth spot ahead of Itagui.
Medellin moved to 24 points, staying ahead of Itagui on goal difference after the latter won 2-0 away to Boyaca Chico.
The first eight clubs in Colombia's top flight qualify for the finals series and the four teams either side of that cut-off point all won in round 17.
In Medellin, the home side fell behind in the first minute of the second half when Sergio Romero scored for Deportivo Cali but Cano's 58th-minute penalty drew the hosts level before Mejia took them into the lead with 21 minutes remaining.
Perez struck in the 83rd minute to wrap up Medellin's win as they maintained a three-game unbeaten streak.
Once Caldas remained one point ahead of Medellin with a 3-0 triumph over Deportes Quindio, while Junior drew 2-2 with 10th-placed La Equidad to remain fifth.
Deportivo Pasto almost snatched a surprise victory over Atletico Nacional after Mauricio Mina scored in the 89th minute but the league-leaders equalised just two minutes later through Orlando Berrio to earn a 1-1 draw.
The stalemate leaves Pasto behind Junior on goal difference, while Nacional top the table with 37 points, nine clear of second-placed Millonarios, who defeated Deportes Tolima 2-1.
In the other match involving clubs around the finals cut-off point, 11th-placed Patriotas Boyaca drew 1-1 with Envigado, who sit 12th.
In other results, Atletico Huila won 2-0 over Alianza Petrolera and Cucuta Deportivo triumphed 1-0 against Santa Fe.
