A 69th-minute penalty from Pablo Hernandez helped O'Higgins to a 1-0 win at home to Huachipato, moving them level on points with Universidad Catolica and Cobreloa.
Eduardo Berizzo's O'Higgins are third because of their inferior goal difference but the victory was their third straight in the league.
Universidad Catolica slipped up for the second straight game and in stunning fashion as they conceded two late goals to draw 2-2 at Deportes Iquique.
Jose Munoz and Ismael Sosa scored in the first half for the league leaders and they looked set for a comfortable victory.
But in a dramatic finish, Gerson Martinez and Manuel Villalobos both struck to secure a surprise point for their seventh-placed side.
Cobreloa would be top had they managed to take anything from their trip to Palestino, who claimed a 2-0 win.
Diego Chaves and Javier Capelli scored for the victors, while Cobreloa had Rene Lima and Cristian Gaitan sent off.
Elsewhere, Universidad Chile were 2-0 winners at Union Espanola and Universidad Concepcion struck late in a 2-1 win at home to Audax Italiano.
Santiago Wanderers completed a 3-0 win at home to Everton, but their victory was marred by five red cards.
Everton had Alex von Schwedler sent off on 11 minutes and were 2-0 down at half-time after Sebastian Pol's brace.
Pol's second goal came in the third minute of additional time before he picked up a second yellow card to be sent off.
Sebastian Mendez and Orlando Gutierrez were red-carded on 55 minutes to see both teams reduced to nine men.
Everton substitute Francisco Dutari was then sent off 10 minutes later and Oscar Opazo ensured Santiago Wanderers took all three points with his goal.
Rangers' struggles continued as they were beaten 3-0 by Nublense, Union La Calera and Antofagasta drew 1-1 and Cobresal were 3-1 winners over Colo Colo.
