Estudiantes go top as Tigre and Boca falter
The leaders are one point clear of Boca and Tigre but Velez Sarsfield can catch them on 15 points with a win at home to Newell's Old Boys on Monday night.
Estudiantes went ahead after only three minutes with a penalty by striker Mauro Boselli. Nicolas Berardo equalised before fellow defender Raul Iberbia tapped in the winner from a low right cross.
The pick of the weekend, though, was the visit of Lanus to the Bombonera and neutrals were not disappointed with a fine match that Lanus might have won against a Boca side down to 10 men for half-an-hour after Clemente Rodriguez was sent off.
The first half ended with a flurry of goals after Boca took the lead in the 39th minute when winger Pablo Mouche exchanged passes with Juan Roman Riquelme at a corner and hit a long, high ball over goalkeeper Agustin Marchesin and into the top corner.
Marchesin had only seconds earlier made a superb diving save from a fine Riquelme effort, giving away the corner.
In the 42nd minute, Boca went two up when a shot by midfielder Diego Rivero was blocked and the ball fell to Riquelme, who shot low into the bottom corner.
Lanus pulled one back a minute later when striker Mariano Pavone headed in a high cross from right-back Carlos Araujo and he celebrated with glee after suffering jibes from Boca fans because he was in the River Plate side relegated last season.
The visitors were level 10 minutes into the second half when central defender Paolo Goltz headed home Uruguayan Mario Regueiro's corner and soon after Lanus's former Italy winger Mauro Camoranesi had a goal disallowed for offside.
Argentina left-back Rodriguez was sent off just past the hour for dissent having just been booked.
Arsenal, who are vying with Boca for a place in the knockout rounds of the Libertadores Cup, ended previous leaders Tigre's unbeaten run when central defender Guillermo Burdisso headed the only goal in Sarandi.