The Jaguares opened their 2019 account thanks to Rodrigo Bruni and Bautista Delguy in Buenos Aires on Saturday.
A pair of late tries gave the Jaguares a 27-12 victory over the Bulls and their first win of the Super Rugby season.
The Jaguares were beaten 25-16 at home to the Lions in round one last week, but the Argentine side opened their account thanks to Rodrigo Bruni and Bautista Delguy.
The Bulls – 40-3 winners last time out – held a 12-9 lead on the hour-mark after fly-half Handre Pollard converted his fourth penalty of the game for the South African visitors in Buenos Aires on Saturday.
But the Jaguares, who led 7-3 at half-time thanks to Matias Orlando's 17th-minute opener, came storming back at a wet Estadio Jose Amalfitani.
Bruni grounded the ball following a rolling maul in the 63rd minute and Joaquin Diaz Bonilla added the extras, before Delguy sealed the victory on the overlap nine minutes later.