Boca Juniors defeated San Martin 1-0 on Sunday to move into second position in the Argentine league after six rounds of matches.
The hard-fought win, obtained without talisman Juan Roman Riquelme, improves the Buenos Aires club to 13 points, one point behind undefeated leader Tigre, which drew 1-1 against Estudiantes on Saturday.
Last weekend, defending league champion Boca lost its 34-game unbeaten run in domestic competition.
In Sunday's other matches, relegation-threatened San Lorenzo drew 1-1 with Colon, with Ariel Hernan Garce equalizing in the 70th for Colon, after an own goal from Adrian Bastia had put San Lorenzo ahead.
Mauricio Sperduti got the goal in the 25th for Newell's in its 1-0 win against Rafaela and Arsenal defeated Banfield 1-0 thanks to a 9th minute goal from Jorge Ortiz.
Uruguayan striker Santiago Silva came close to opening the scoring for Boca with a back post header in 45th.
The former Fiorentina player had a similar opportunity 15 minutes after halftime, but it went just wide of the post.
Boca's goal came in the 71st, when Walter Erviti scored with a low left foot shot from inside the penalty area after a backheel pass from Silva helped open up the San Martin defense.
Three minutes later, Cristian Grabinski headed just over the crossbar for San Martin, which piled pressure on Boca in the last few minutes.
On Saturday, Mauro Boselli opened the scoring for Estudiantes in the 18th minute, but Diego Morales equalized from the penalty spot ten minutes later.
In Friday's games, Lanus lost 1-0 to Argentinos and All Boys and Godoy Cruz drew 1-1.
In Saturday's other games, Union and Velez drew 3-3, Independiente won 2-0 against Belgrano and Racing defeated Olimpo 3-0.
