Runners-up last season, the Jaguares ran away with a comfortable win over the Lions.
The Jaguares cruised to victory in their opening game of the Super Rugby season, while the Stormers also started their campaign in style on Saturday.
Last season's runners-up, the Jaguares eased to a 38-8 victory over the Lions in Buenos Aires.
It took until the second half for the Jaguares to run away with their win, having led 10-8 at the break.
Matias Moroni crossed for two second-half tries and Javier Ortega Desio and Agustin Creevy also went over, with not even Marcos Kremer's yellow card shortly after the interval able to slow the Jaguares.
The hosts ended up scoring 31 unanswered points after the Lions had taken an 8-7 lead midway through the first half.
The Stormers began their campaign in style, easing to a 27-0 home victory over the Hurricanes.
The visiting Hurricanes reached the semi-finals of the competition last season but were blown away in the opening 40 minutes on Saturday.
A dominant Stormers start led to Sergeal Petersen's opening try, before a drive from Steven Kitshoff led to a quick second.
The third try came soon enough, too, as Herschel Jantjies punished a stray pass in ruthless fashion.
Although the second half was less eventful, two Hurricanes yellow cards – for Billy Proctor and Vaea Fifita – preceded Damian Willemse's stunning 90-yard sprint for the final try