Both sides scored three tries apiece but Nicolas Sanchez’s boot made sure the visitors – who had recorded a 25-22 win over the Rebels in the last round – moved above the Stormers and off the foot of the South African Conference.
The fly-half also had a hand in the game’s opening try, as his offload allowed Matias Orlando to plunge over in the fifth minute at GIO Stadium.
Sanchez added the extras and was also on target with a pair of first-half penalties, putting the Jaguares 13-0 ahead in the early stages.
The hosts were given a further boost when Emiliano Boffelli was sin-binned early in the second half for taking out Henry Speight in the air, yet it was the Jaguares who crucially scored next thanks to Jeronimo de la Fuente’s converted try.
Chance Peni’s close-range finish, with Hawera successfully converting, cut the gap back down to three, but Boffelli made amends for his earlier indiscretion by touching down nine minutes from the end.