League leaders Santa Fe and second-placed Once Caldas played out a goalless draw at Estadio Nemesio Camacho on Saturday.
The stalemate, however, was enough for Santa Fe to maintain their lead atop the table after Medellin lost 3-2 at home to Deportes Tolima earlier on Saturday.
Santa Fe are one point clear of Once Caldas through 15 games, while Medellin are a further point back.
Medellin - beaten 2-1 by Alianza Petrolera in their previous home match - found themselves two goals down two minutes into the second half.
Charles Monsalvo opened the scoring for Deportes Tolima on the half-hour mark and Breyner Bonilla doubled the visitors' lead in the 47th-minute.
Medellin pulled a goal back four minutes later via Jefferson Mena, but Yimmi Chara restored Deportes Tolima's two-goal cushion two minutes later.
The home side reduced the deficit once again within two minutes courtesy of Javier Calle but Deportes Tolima held on for maximum points as Vladimir Marin saw red for Medellin in injury time.
In other results, fourth-placed Alianza Petrolera were held to a scoreless draw by second-bottom Uniautonoma.
Miguel Murillo netted a hat-trick as Deportivo Cali - fifth in the table - twice came from behind to beat lowly Millonarios 4-3 in a thriller.
Atletico Nacional ended their run of back-to-back defeats, edging Junior 1-0 thanks to Jonathan Copete.
Jair Palacios, Yamith Cuesta and Norbey Salazar were on target as Fortaleza accounted for basement side La Equidad 3-0.
Aguilas Pereira overcame Boyaca Chico 3-2 after Edison Palomino converted an 80th-minute penalty.
Meanwhile, nine-man Envigado were beaten 2-1 at Patriotas Boyaca and Atletico Huila disposed of Deportivo Pasto 3-0.
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