Argentina recorded an immediate response to their defeat to England by teaching Romania a rugby lesson in a 43-8 win in Invercargill on Saturday.
The Pumas were full value for their win in a one-sided Pool B encounter that saw seven tries being scored - six of them to Argentina.
Santiago Fernandez, Juan Manuel Leguizamon, Juan Figallo, Lucas Gonzalez Amorosino, Florin Vlaicu and Genaro Fessia all crossed for tries - and Argentina could have scored more but for some desperate Romanian defending.
There was also am improved showing with the boot as centre Martin Rodriguez, who was guilty of missing too many efforts in the 13-9 loss to England, was more accurate this time as he added 13 points from the kicking tee.
He missed an early penalty attempt with barely three minutes up on the clock but made up for his blunder by converting Argentina's opening try to pivot Fernandez, who strolled over in the sixth minute.
The Pumas wasted little time in scoring their second when - just two minutes later - flanker Leguizamon used his pace and power to charge through two would-be defenders to crash over beside the posts.
Romania had hardly touched the ball twelve minutes into the match, but were rewarded for their best spell of pressure with a penalty and fly-half Tiberius Dimofte made no mistake.
However, the Pumas extended their lead even further when prop Figallo burrowed his over from close range before full-back Amorosino secured Argentina's four-try bonus point when he broke through some tired tackling after a concerted spell of pressure.
Romania weren't prepared to roll over that easily though and hit back with a try through wing Ionel Cazan, who flew over in the corner after the Oaks had stretched the Pumas defence for the first time in the match.
Dimofte missed the conversion as well as a penalty attempt on the stroke of half-time that saw Romania head into the break 26-8 down.
Argentina started the second half in the same fashion they began the first - with a missed penalty followed by a successful one through Rodriguez.
Romania kept the Pumas tryless until prop Mihaita Lazar was sin-binned for repeated infringements.
Argentina finally broke the Romania resistance when replacement back Juan Jose Imhoff stepped and then showed electric acceleration to score a converted try under the sticks.
Romania thought they had hit back when Dimofte intercepted and found Daniel Carpo in support. The number eight shipped the ball to Cazan but as the winger attempted to keep the move alive, Argentina were able to hack the ball on - with replacement flanker Fessia picking up and running in unopposed to score.
Game, set and match Argentina!
The win sets up a showdown with Scotland in Wellington next Sunday with the winner in pole position to ensure a slot in the quarter-finals, while the east Europeans are now set to make it seven straight failures to get out of the pool stages at the World Cup.
Tries: Fernandez, Leguizamon, Figallo, Amorosino, Imhoff, Fessia
Con: Rodriguez 5
Argentina: 15 Lucas González Amorosino, 14 Gonzalo Camacho, 13 Martin Rodriguez, 12 Marcelo Bosch, 11 Horacio Agulla, 10 Santiago Fernandez, 9 Nicolas Vergallo, 8 Juan Martin Fernandez Lobbe, 7 Juan Manuel Leguizamon, 6 Julio Farias Cabello, 5 Patricio Albacete, 4 Manuel Carizza, 3 Juan Figallo, 2 Mario Ledesma, 1 Rodrigo Roncero.
Replacements: 16 Agustin Creevy, 17 Martin Scelzo, 18 Mariano Galarza, 19 Alejandro Campos, 20 Alfredo Lalanne, 21 Nicolas Sanchez, 22 Juan Jose Imhoff.
Romania: 15 Iulian Dumitras, 14 Madalin Lemnaru, 13 Csaba Gal, 12 Constantin Gheara, 11 Ionel Cazan, 10 Tiberius Dimofte, 9 Florin Surugiu, 8 Daniel Carpo, 7 Ovidiu Tonita, 6 Mihai Macovei, 5 Cristian Petre, 4 Valentin Ursache, 3 Paulica Ion, 2 Marius Tincu (c), 1 Mihaita Lazar.
Replacements: 16 Bogdan Suman, 17 Silviu Florea, 18 Valentin Poparlan, 19 Daniel Ianus, 20 Valentin Calafeteanu, 21 Marin Dumbrava, 22 Florin Vlaicu
Referee: Steve Walsh (Australia)