Velez Sarsfield have won the Argentine first division title with a 2-0 victory over Union.
Second-half goals from Facundo Ferreyra helped the Buenos Aires club open up an unassailable five-point lead at the top of the table and clinch the Inicial championship.
This is Velez's first Inicial championship triumph in 17 years and their ninth domestic title in history.
"They said it was a time of transition but we showed from the start that we'd go for the championship," said Velez president Miguel Callelo.
"The title is the result of consistent hard work and a clear commitment to our aims. [Coach] Ricardo [Gareca] knows that we want to continue along this winning path and achieve the goals that we are yet to meet."
The domestic season in Argentina is divided into two championships, the Inicial and the Final, which will start in February. The winners of the two championships will meet each other in a grand final in June, unless the same side win both.