Scrumhalf Andre Warner scored the visitors' only try while flyhalf Elton Jantjies kicked a penalty goal in response to the hosts' five tries.
The visitors restricted the home team to a slender 10-8 halftime lead, however, the Jaguares scored four second half tries to secure a superb home victory.
The home side conceded a lot of penalties in the match, including seven in the first half alone, and their flanker Marcos Kremer received a yellow card in the second half for a dangerous tackle off the ball.
However, the Emirates Lions failed to take advantage and instead it was the Jaguares who increased the tempo which resulted in two quick tries for outside centre Matias Moroni.
The Jaguares scored their fourth try with 10 minutes to go, when substitute Javier Ortega Desio dotted down and just before the end Agustin Creevy (hooker) crossed for their fifth try from behind a rolling maul.
Jaguares (10) 38 - Tries: Domingo Miotti, Matias Moroni (2), Javier Ortega Desio, Agustin Creevy. Conversions: Domingo Miotti (5). Penalties: Domingo Miotti.
Lions (8) 8 - Tries: Andre Warner. Penalties: Elton Jantjies.