Velez Sarsfield clinched its ninth Argentine first division title with a 2-0 win in the second-to-last match of the season.
The victory at home over Union left the century-old Buenos Aires club five points ahead of its closest rivals, Lanus and Belgrano.
Velez has won 12 of its 19 matches this season and lost only 4.
The team didn't look like a title contender at the start of the season. Eight veterans had left after a third-place finish in the previous tourney and a quarterfinal exit from the Copa Libertadores.
Besides turning to Velez's reserve and youth squads, coach Ricardo Gareca made some key acquisitions, including striker Facundo Ferreya, who was picked up from relegated Banfield and went on to lead the first division in scoring.
Velez Sarsfield is also one of the most solid Argentine clubs from a business standpoint, thanks in part to its ownership of a stadium and 18 hectares (44 acres) of prime real estate in Buenos Aires. EFE