Southern Kings have held on to beat Jaguares 31-30 in their Super Rugby clash at the Estadio Jose Amalfitani in Buenos Aires.
Friday's game was the first competitive game for both sides after a month-long break for internationals.
The home side led 20-14 at halftime but tired in the second half.
Many of the Jaguares players have just finished three weeks of Test duty for Argentina.
The Jaguares, who scored five tries to the Kings' four, still could have pulled out a win but Joaquin Diaz Bonilla missed a sideline conversion in the 75th minute before the hosts lost a lineout while threatening to score in the final minute.
Both teams have won five of 13 games this season and have long been out of the running for a finals spot.