Emelec slumped to a 2-0 defeat against Carlos Sevilla's side last weekend and were then beaten 2-1 by Brazilian side Flamengo in the Copa Libertadores on Thursday.
But Gustavo Quinteros' charges ended a poor week on a high note as they swept aside fourth-placed El Nacional with a clinical performance.
Cristian Nasuti set them on their way with a goal after 27 minutes, then Miller Bolanos stunned the visitors with a second goal two minutes later.
Jorge Valencia halved the deficit 13 minutes after the break, but Marcos Caicedo added a third goal from the penalty spot 10 minutes from time before further strikes from Angel Mena and Javier Charcopa added insult to injury.
That victory ensured Emelec maintained their one-point advantage over Independiente Del Valle, who had taken over at the summit with a 2-1 win over struggling Mushuc Runa on Friday.
Maximiliano Barreiro gave Runa a sixth-minute lead and they looked set to pull off a shock win before Junior Sornoza kept his nerve to equalise from the spot seven minutes from time and Gabriel Cortez won it a minute later.
Third-placed LDU Loja slipped up on Saturday as they were consigned to a 4-2 defeat at Manta, who were indebted to two goals from Jorge Palacios Avila.
There was more misery for bottom-of-the-table Deportivo Cuenca, who have only won one league victory to their name this season after they were beaten 1-0 at home by Deportivo Quito.
In the other games to be played on Sunday, Armando Wila scored both goals in Universidad Catolica's home victory over Barcelona and Olmedo were 1-0 winners of LDU Quito.
