Supporters of Uruguayan clubs Danubio and Nacional fought on the pitch after the top-of-the-table match on Sunday which the hosts won 1-0.
There was also a pitch invasion in Peru where Universitario supporters attempted to attack their own players after they conceded a late equaliser in a 1-1 draw at Atletico Minero
Danubio leap-frogged Nacional to go top of the championship's first stage after their 1-0 win but the match was overshadowed when fans fought on the field.
Shortly after the final whistle, dozens of visiting Nacional fans found their way through a hole in the fencing, invaded the pitch and managed to grab a Danubio flag.
This enraged the home supporters who also ran onto the field and a pitched battle ensued in which fans, some armed with iron bars, punched and aimed karate kicks at each other.
Media said that police took around 15 minutes to bring the situation under control.
A crowd of around 7,000 had packed into Danubio's tiny ground in the working-class neighbourhood of Jardines del Hipodromo.
Jorge Garcia headed the only goal in the second half from Sergio Leal's cross while Nacional had Adrian Romero sent off in the last minute.
Danubio lead with 24 points from 11 games, two ahead of Nacional and Cerro.
• Around 100 Univeristario supporters ran onto the field and attempted to attack the players after the 1-1 draw away to Atletico Minero in Matucana. The fans also insulted the team and demanded the resignation of coach Ricardo Gareca.
The players left the field under police protection, went straight onto the team bus and headed for Lima, a journey of around four hours, without having a shower.
Roberto Jimenez put Universitario ahead but Jose Galvan snatched a late equaliser for lowly Atletico to the fury of the roughly 1,000 visiting supporters.
Sport Ancash's joy at being awarded the three points from their 1-0 defeat at home to Deportivo San Martin was short-lived as they lost 1-0 to Sporting Cristal.
Ancash were awarded a 3-0 walkover win last week because San Martin had arrived late for the game, a decision which left both teams level at the top of the championship's second stage with 40 points each.
San Martin went three points clear by winning 2-0 at Coronel Bolognesi with long-range goals from Ronald Quinteros and Jose Diaz.