The Jaguares have scored three tries, the decisive third a penalty try, to beat the Stormers 30-25 in a tense Super Rugby clash.
A fourth consecutive victory has lifted the Argentines to sixth in the combined standings, keeping them in contention for a top-eight finish and a play-off slot.
The Jaguares led from beginning to end at Estadio Jose Amalfitani, after an early try by flanker Pablo Matera.
However, their ill-discipline allowed the Stormers to keep in touch throughout with six successful penalty kicks, four by flyhalf Jean-Luc du Plessis and two in the second half by fullback Damian Willemse.
Winger Ramiro Moyano scored the Jaguares’ second try early in the second half and they were awarded a penalty try 10 minutes from time for a deliberate knock-on by JJ Engelbrecht, who was sent to the sin bin.
The Stormers went over for a late try by replacement winger Seabelo Senatla but could not deny the Jaguares the win.
The South Americans are only a point behind the Bulls and the Sharks in third place in the South African conference.
The Jaguares start a four-match Australasia tour next Saturday against the Highlanders in Dunedin while the Stormers have a bye.