Juan Reynoso's Melgar have four wins from as many games and are yet to concede after a 1-0 victory at home to Union Comercio.
Bernardo Cuesta's neat run in behind and good finish in the first half saw Melgar to their most recent win.
It saw Melgar maintain their three-point lead at the top, while Universitario returned to winning ways.
Raul Ruidiaz's 68th-minute strike was enough for a 1-0 win at home to Los Caimanes, who had Josias Cardoso sent off.
Elsewhere, Santiago Silva struck a brace as Universidad San Martin had a come-from-behind 4-1 win over Sport Huancayo.
Cesar Valoyes' first-half effort saw UTC Cajamarca past Cesar Vallejo 1-0.
Real Garcilaso's struggles continued as they were beaten 2-0 at home to Cienciano.
Martin Icart and Miguel Ximenez scored in the first half to leave Real Garcilaso winless and second bottom.
Only San Simon are below them, but the battlers did collect their first point of the season with a 2-2 draw at home to Leon de Huanuco.
Carlos Preciado hit a brace for the visitors as they came from behind twice before being reduced to 10 men when Anderson Santamaria saw red.
Alianza Lima were held to a 0-0 draw at Juan Aurich, while Inti Gas and Sporting Cristal played out a 3-3 draw.
