Carlos Tevez helped Boca Juniors clinch the Argentinian Primera Division title with a 1-0 win over Gimnasia y Esgrima La Plata on Saturday.
Tevez's 20-yard strike in the 72nd minute at La Bombonera lifted Boca to their narrow victory over Diego Maradona's Gimnasia.
It meant Boca finished top of the table by a point after bitter rivals River Plate were held to a 1-1 draw at Atletico Tucuman.
Boca's title was their 34th, drawing them closer to River's all-time record of 36.
Tevez's goal was his ninth in 17 league games this season, with Gimnasia goalkeeper Jorge Broun unable to keep out the powerful effort.
River, meanwhile, had come from behind at Atletico Tucuman through Matias Suarez, but were unable to find a winner.
They were held to draws in their final two league games of the season.