While the pacesetters were being held by Santos Laguna, Mancilla was helping Tigres Monterrey - the league's only unbeaten team - rout Pachuca 5-0.
The home side led 3-0 at the interval with two goals from Mancilla and another from Lucas Lobos, Segunda Castillo made it 4-0 with an own goal, before Mancilla rounded off the scoring.
Guadalajara needed a 73rd-minute goal from Alberto Medina to earn a draw at Santos Laguna, who led through Rafael Figueroa's 51st-minute effort.
Carlos Bueno was another player to score a hat-trick in Queretaro's 4-0 defeat of Unam Pumas.
Substitute Franco Niell rounded off the scoring just the hour mark as the home side leapfrogged their opponents in the standings, in a match which saw Queretaro's Israel Martinez and the visitors' Fernando Espinosa dismissed five minutes into the second half.
A last minute goal from Joao Rojas earned Morelia a surprise 1-0 win at third-placed Cruz Azul, while bottom club Atlas earned a point from a 1-1 home draw with San Luis - with Michael Arroyo's goal cancelling out San Luis team-mate Anibal Matellan's 37th-minute own goal.