Racing won their first Argentine league title since 2014 on Sunday when a 1-1 draw away to Tigre, combined with a slip up by their closest challenger, gave them an insurmountable lead with just one game of the season left.
Racing took the lead after 57 minutes through Augusto Solari but even though Lucas Rodriguez equalised in stoppage time the point was enough.
It meant the club from Avellaneda have 56 points from 24 games, four ahead of Defensa y Justicia with just one game remaining.
Defensa y Justicia, a small club from the outskirts of Buenos Aires who only debuted in Argentina's fourth tier in 1978, had never won a major title before and they stuttered in the run in, losing two of their last five matches and drawing 1-1 at home on Sunday with Union Santa Fe.
Racing, however, have led the league since the fourth match of the season and kept accumulating points to clinch the Superliga, the 18th league title in their history.
Racing have long been known as one of Argentina's big five clubs but they have been hit by a series of financial difficulties over the last few years and this is only their third league triumph since 1966.
The premature denouement robs fans of what could have been a thrilling end to the title race with Racing at home to Defensa y Justicia in the final game next Saturday.