Queensland have let another Super Rugby lead slip as the Jaguares fought back from conceding four first-half tries to eventually steamroll the visitors in Argentina.
Last year's grand finalists won 43-27 after the Reds' led 24-7 at halftime courtesy of a superb first 40 minutes.
But, like in losses to the Brumbies and South Africa's Lions, Brad Thorn's Queensland were left to rue lazy errors and cheap penalties as they face the grim reality of returning home to Brisbane winless.
Reds halves Tate McDermott and James O'Connor were brilliant in the first half while winger Chris Feauai-Sautia scored two tries to cap off brilliant interplay.
Liam Wright and Tate McDermott also scored five-pointers as the Reds silenced Jose Amalfitani Stadium.
Into the side for injured centre Jordan Petaia, Hunter Paisami was tremendous and only stopped by an ankle tap as the line beckoned while the Reds still led midway through the second half.
O'Connor then stepped his way through traffic but lost possession trying to plant the ball. A harsh scrum penalty followed and the hosts marched upfield to score in what proved the pivotal moment.
The Reds were hammered 14-3 in the penalty count by hometown referee Federico Anselmi, captain Wright yellow carded trying to pilfer while defending his line.
His absence allowed the Jaguares to go in again as captain Julian Montoya scored a third try from their unrelenting rolling maul to hand the hosts the lead with 17 minutes to play.
"The key moment was the scrum; we absolutely dominated and destroyed them and we get penalised," Thorn said.
"That's very hard to understand. The last two weeks it's (the scrum) been doing the business and five metres out, a key moment in the game, that was a hard one to understand.
"The guys played outstandingly well and there was a lot to like but that second half - I think it ended in a 15-3 penalty count ... that's a tough one to contend with."
Montoya sacrificed a chance to equal a Super Rugby-best four try haul, with his replacement Santiago Socino scoring in identical fashion to seal the win.
The loss left the Reds with just two bonus points from a tough three-game tour to begin the season.
Their next game is their home opener against Japan's Sunwolves on Saturday.