David Trezeguet gave River the lead in the 11th minute when Colon goalkeeper Diego Pozo spilled Leonardo Ponzio's free kick and the former France striker tapped the ball in.
Midfielder Ponzio increased their lead in the 33rd minute with a fine finish that looped over Pozo before striker Emanuel Gigliotti pulled one back for Colon 16 minutes from time.
River, after their fourth win in five matches, lead with 12 points from five matches. They are a point ahead of Godoy Cruz and two in front of Lanus, who can reclaim the lead with a win at home to Arsenal on Monday.
Local media reported that a River fan had been stabbed on an avenue close to the ground before the "Final" championship match as violence continues to plague Argentine football.
There have been two deaths in the last week as a result of football-related incidents of violence.
On Saturday, Racing Club were coasting to a 3-0 victory at San Martin when referee Carlos Maglio abandoned the match in the 87th minute as hooligans hurled objects onto the pitch and attempted to break down perimeter fencing.
Police used fire hoses to try to stop the violence but to no avail.
San Martin coach Gabriel Perrone, who during the week suggested his team's rivals were favoured by referees after last weekend's 3-0 defeat away to champions Velez Sarsfield, resigned.
The Argentine Football Association is expected to confirm Racing won the match while San Martin remain in relegation trouble after 13 matches without a victory.
- Sports & Recreation
- Leonardo Ponzio
- Diego Pozo