The Waratahs' strong finish was not enough to bring home a win against the Jaguares, going down 28-38 to the Jaguares in Buenos Aires on Saturday.
A physical game across the park, the set piece was given a work out with a total of 21 line-outs and 15 scrums.
It was the home team who struck first blow through Emiliano Boffelli, who finished off a team try to score within the first minute of the game.
The Waratahs looked to gain control, stringing together 14 attacking phases in the fifth minute but to no avail.
The Jaguares' counter-attack proved unstoppable, turning the ball over and working their way into the Waratahs' half for Boffelli's second of the evening to make it 14-0 after nine minutes.
A Bernard Foley restart, regained by Kurtley Beale, sparked another Waratahs' attempt at the line which came metres from resulting in points, only to be foiled by some brave Jaguares defence.
Following two more Argentinian tries in fullback Joaquin Tuculet and flyhalf Nicholas Sanchez, the visitors found themselves 0-26 down at the 20-minute mark.
The Waratahs were given some inspiration from a bone-rattling Michael Wells tackle that forced a Jaguares ball free, setting up the platform for an attack in the 33rd minute.
Jed Holloway spotted a gap in the Jags' defence just two minutes later, going over untouched just under the sticks for his fourth career try.
Mario Ledesma's side entered the sheds ahead 33-7 over the visitors.
The second half brought with it a re-energized Waratahs side; wing Curtis Rona finishing off a team try in the 47th minute to put up his first points in Waratahs colours, the scores sitting at 33-14.
After plenty of back and forth between the two sides, the Waratahs' bench made its way onto the field with 20 minutes left on the clock to up the tempo for the Tahs.
But relentless set-piece pressure prevailed for the Argentinians, scoring in the corner through centre Matias Orlando in the 73rd minute to push the deficit to 38-14.
With time not on the Tahs' side, the team worked hard to finish on a high note. Replacement lock Nick Palmer scored his first points for the Waratahs, finishing off the hounding attack in the 79th minute.
38-21 and the final hooter been-and-gone, utility back Bryce Hegarty broke the Jaguares' line inside the Waratahs' 50m before punching through a well-placed grubber for Israel Folau to dot down over the line.
Flyhalf Bernard Foley remains 100 percent with the boot in 2018, knocking all four conversions over.
Tries: Boffelli 2, Tuculet, Sanchez, Delguy, Orlando
Cons: Sanchez 4
Tries: Holloway, Rona, Palmer, Folau
Cons: Foley 4
Jaguares: 15 Joaquin Tuculet, 14 Bautista Delguy, 13 Matias Orlando, 12 Santiago Gonzalez Iglesias, 11 Emiliano Boffelli, 10 Nicolas Sanchez, 9 Gonzalo Bertranou, 8 Javier Ortega Desio, 7 Marcos Kremer, 6 Pablo Matera, 5 Tomas Lavanini, 4 Matias Alemanno, 3 Nahuel Tetaz Chaparro, 2 Agustin Creevy, 1 Felipe Arregui.
Replacements: 16 Julian Montoya, 17 Santiago Garcia Botta, 18 Juan Pablo Zeiss, 19 Guido Petti Pagadizaval, 20 Juan Manuel Leguizamon, 21 Felipe Ezcurra, 22 Joaquin Diaz Bonilla, 23 Sebastian Cancelliere.
Waratahs: 15 Israel Folau, 14 Alex Newsome, 13 Lalakai Foketi, 12 Kurtley Beale, 11 Curtis Rona, 10 Bernard Foley, 9 Jake Gordon, 8 Jed Holloway, 7 Michael Hooper (captain), 6 Michael Wells, 5 Tom Staniforth, 4 Ned Hanigan, 3 Paddy Ryan, 2 Damien Fitzpatrick, 1 Tom Robertson.
Replacements: 16 Tolu Latu, 17 Harry Johnson-Holmes, 18 Kalivati Tawake, 19 Nick Palmer, 20 Will Miller, 21 Nick Duffy, 22 Bryce Hegarty, 23 Taqele Naiyaravoro.
Referee: Mike Fraser (New Zealand)
Assistant referees: Nick Briant (New Zealand), Pablo Deluca (Argentina)
TMO: Santiago Borsani (Argentina)