Ronaldo returned to the field for Corinthians in the Brazilian league on Sunday, with two dubious offside calls denying him a goal in his comeback from injury.
Despite a 0-0 draw with Guarani, Corinthians still edged to within four points of the top spot after leader Cruzeiro lost 2-1 at Gremio.
In Argentina, Velez Sarsfield and Arsenal both claimed weekend wins to cut Estudiantes' lead in the Apertura tournament to three points with eight games remaining.
Velez won 2-1 at Quilmes on Friday, while Arsenal had a 3-2 win at Gimnasia. Estudiantes could only draw 1-1 at Colon. In Mexico, leader Cruz Azul won 3-0 at third-placed Santos to stay two points clear of Monterrey, which had a 2-0 home win against Toluca.