Ismael Blanco and Jose Luis Perlaza struck second-half goals for Ruben Israel's men, who have six wins from eight league matches.
El Nacional are six points back but have a game in hand, as do third-placed LDU Quito.
Barcelona continue to be pacesetters and got the job done against Olmedo at Estadio Monumental Isidro Romero Carbo.
Blanco volleyed in the opener in the 49th minute after Christian Suarez's effort from an angle was parried.
It was 2-0 just before the hour-mark as Perlaza headed in a set-piece to seal the win.
Felipe Mejia struck a hat-trick as El Nacional thrashed Deportivo Quito 4-0.
Mejia scrambled in the opener in the 33rd minute, but the visitors had to wait until the second half to go further ahead.
Again it was Mejia, who had to stretch at the back post to get on the end of a cross to make it 2-0.
Mejia tapped in the easiest of third goals to complete his hat-trick in the 64th minute before Marwin Pita also got on the scoresheet.
Third-placed LDU Quito enjoyed a 2-0 win at home to Manta and Mushuc Runa came from behind to draw 1-1 at Deportivo Cuenca.
LDU Loja and Independiente del Valle played out a scoreless draw.
The clash between Universidad Catolica and Emelec was postponed as both compete in the Copa Sudamericana.
