Two second half goals helped ten-man River Plate to a 2-1 victory over Belgrano on Sunday, while archrivals Boca Juniors won 3-2 against Quilmes on Saturday in the opening round of fixtures in Argentina's Torneo Final championship.
The games marked the return of famous managers to the Buenos Aires giants, with Ramon Diaz moving back to River and Carlos Bianchi to Boca in the offseason.
In other results on Sunday, Newell's Old Boys got a 3-1 victory against Independiente and Rafaela defeated Racing 3-0.
On Saturday, All Boys and Godoy Cruz drew 1-1, Tigre won 3-1 against Estudiantes and San Martin drew 0-0 against San Lorenzo.
In previous spells with River, Diaz won the league title five times, the Copa Libertadores and the Copa Sudamericana.
It took until the 67th minute for his side to break through, with Leonel Vangioni striking a fierce left foot shot into a corner of the net from 25 yards (meters).
Carlos Luna doubled the lead in the 88th when he latched onto a flick on from a long ball and finished.
Guillermo Farre pulled a goal back for Belgrano from close range one minute later.
All the goals came after River's Leonardo Ponzio was sent off right after halftime.
Bianchi has won four league titles and three Copa Libertadores for Boca, but his team was 2-0 down inside 10 minutes.
Wilfredo Olivera headed in the first for Quilmes in the 5th and Cristian Menendez increased the lead with a chipped finish in the 9th.
Walter Erviti got one back for Boca in the 38th from close range, before Guillermo Burdisso handed Boca the victory with a second half double.
His equalizer came in the 68th from a freekick swung in from the right, and his second was a volley drilled in from the edge of the penalty area.
Ignaccio Scocco scored in the 17th and 77th for Newell's Old Boys with Pablo Perez wrapping up the scoring in the 82nd.
Independiente's goal came in the 21st through Cristian Tula.
Lucas Bovaglio converted a penalty for Rafaela's first in the 28th, with Sebastian Grazzini adding the second, again from the penalty spot, on the stroke of halftime.
Jonathan Lopez got the third for Rafaela four minutes into the second half.
Oscar Ahumada rescued a point for All Boys with a goal in the 77th, after Facundo Castillon had given Godoy Cruz the lead in first half injury time.
Tigre's goals came from Ruben Botta in the 28th, Alejandro Donatti in first half stoppage time and Gabriel Penalba in the 76th.
Marcos Gelabert had given Estudiantes the lead in the 9th.
San Martin and San Lorenzo played out a scoreless draw with few chances.
In Friday's games, reigning champion Velez Sarsfield defeated Argentinos Juniors 1-0, with Lucas Pratto scoring in first half stoppage time.
Dario Benedetto snatched a draw in second half stoppage time for Arsenal against Union Santa Fe, which had taken the lead through a goal from Brahian Aleman, in Friday's other game.
The final game of the opening round of fixtures between Lanus and Colon will take place on Monday.