Peru Wrap: Juan Aurich salvage stalemate
Hernan Rengifo equalised in the third minute of injury time for Roberto Mosquera's visitors, denying Melgar a win that would have seen them match second-placed Sporting Cristal on 23 points.
Instead, Melgar sit three points behind Clausura leaders Alianza Lima, and will lose Nelinho Quina to suspension after he was sent off in the 89th minute.
Melgar remain two points above fourth-placed Union Comercio, who sunk Cesar Vallejo 2-1 courtesy of a late goal.
Joao Villamarin struck in the 90th minute at the Estadio del IPD after the two sides traded penalties, inflicting Cesar with their third straight defeat.
UTC Cajamarca moved away from the bottom two, with a 3-0 thrashing of cellar-dwellers San Simon.
Each of San Simon and Universidad San Martin have just seven points this season, but UTC moved to 11 with their third win of the campaign.
Inconsistent Cienciano were 2-0 victors over Sport Huancayo courtesy of Rodrigo Camino's double.
Cienciano have alternated home wins with away losses since their road win over Real Garcilaso in September.
Leon de Huanuco fell to a third straight loss, going down 3-2 to Los Caimanes - the winners climbing to seventh on the back of their third win in five.
Inti Gas joined Real Garcilaso on 14 points with a 2-0 win over their mid-table rivals, while Universitario moved fifth with a 3-1 victory over strugglers Universidad San Martin.