Ruben Israel's Barcelona (25 points) remained one point clear of Independiente, after edging El Nacional 1-0 at home on Sunday.
Christian Suarez's 68th-minute goal was the difference, taking Barcelona to their eighth win in 11 matches in the season's second phase.
Suarez, laying against the side he scored 12 goals for in the 2010 campaign, volleyed home with his left boot for his sixth Primera A goal for Barcelona.
Independiente have a game in hand, and stayed within Barcelona's reach, after a 1-0 road win at Deportivo Cuenca.
Pablo Repetto's side battled to the three points despite going down to 10 men when Jonathan Gonzalez was sent off in the 35th minute.
Jefferson Orejuela scored what was the winner on 58 minutes, while Independiente's task was made much easier when Cuenca's Galo Ricardo Corozo was dismissed five minutes later.
Emelec dropped four points behind Independiente in third, after being held to a 2-2 draw at Deportivo Quito.
It could have been much worse for the visitors too, as they trailed 2-0 after first-half goals to Jonathan Hansen and Walter Calderon.
But Miller Bolanos pulled one back for Emelec in the 66th minute, and Angel Mena scored the equaliser with two minutes of regulation time to play.
LDU Quito joined Emelec on 20 points, courtesy of a rampant 5-1 win over Mushuc Runa.
Only one point separated the two sides prior to kick-off, but braces to Juan Luis Anangono and Diego Morales saw them saunter past the mid-table club.
Mushuc Runa remain in the top six, as LDU Loja - two points back in seventh - were humbled 2-1 at home to Universidad Catolica on Saturday.
Catolica have now won three of their past four to sit in ninth on 11 points.
Also on Sunday, Olmedo won the battle of the bottom two against cellar-dwellers Manta 1-0 to put six points between the two sides.
It was Olmedo's first win of the season, taking them to nine points and leaving Manta with just three draws to show from 12 fixtures.
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