In the last of three World Cup matches played at Rugby Park Stadium, New Zealand's southernmost city turned on its best spring weather — sunny but cool — and its most vocal crowd highlighted by singing, chanting South Americans enjoying the Pumas' win.
Argentina dominated the setpiece and breakdown despite losing to England 13-9 last weekend. The Pumas pack again dominated against Romania, but this time the backline unleashed some potent attack to lead 26-8 by halftime.
Santiago Fernandez, Juan Manuel Leguizamon, Juan Figallo and Lucas Gonzalez Amorosino, voted man of the match, scored the first-half tries, converting Argentina's glut of possession into a substantial lead. In the second half, replacements Juan Jose Imhoff and Genaro Fessia added Argentina's fifth and sixth tries.
Centre Martin Rodriguez kicked five conversions and a penalty for 13 points. Winger Iionel Cazan scored the lone try for Romania, while Tiberius Dimofte kicked a penalty.
Juan Martin Fernandez Lobbe, standing in for injured Argentina skipper Felipe Contepomi, said the performance was "patchy" at times, but he was still pleased with the mental boost it will provide.
"The idea was to have a good game for us, to have a win, but also to have a game plan that gave us confidence," Fernandez Lobbe said.
He thought there was room for improvement ahead of Argentina's next match Sept. 25 against Scotland.
"I thought sometimes we went away from our game plan and we tried to throw the ball around without doing the basics well, and it got a little bit messy," he said. "But when we got back to our system it was a good, good performance."
Santiago Fernandez agreed that Argentina was not consistent.
"I think we played very well for 30 minutes, then the team got very disorganized," he said. "It was important for us to win this way after losing our first match."
Argentina coach Santiago Phelan was asked whether it was the best performance by the team since he became coach in March 2008.
"Not the best, not the worst, but a very important game," he said. "We needed a good score."
"It's important that Argentina scored many points which is something we haven't done for some time. "
Romania, which lost 34-24 to Scotland in its first Pool B match, should have known they were in for a rough afternoon when Legiuzamon ran straight over Florin Surugui, knocking the Romanian scrumhalf onto his back, as he barged over in the eighth minute for the Pumas' second try.
It wasn't pretty for the rest of the half, either, with Romania forced to make 62 tackles against Argentina's 20. For the match, it was 127 to 56.
And Romania missed 23 tackles in the match trying to stop the relentlessly running Argentinians, much to the delight of the Argentinian fans in the crowd, some wearing large puma heads and blue-dyed wigs.
The Romanians weren't helped when prop Mihaita Lazar was yellow carded in the 54th minute, giving Argentina a one-man advantage for 10 minutes in the second half.
With the match all but decided by halftime, both teams made ample use of the reserves bench. Argentina brought in all seven, while Romania's replacement hooker Bogdan Zebega Suman was the only player from the losing side not to make the field.
For Argentina, hooker Mario Ledesma set a national World Cup record by playing his 15th match. The 38-year-old Ledesma, who previously shared the record with Agustin Pichot and Contepomi, was one of those replaced after halftime.
Forwards Cristian Petre and Ovidiu Tonita played their 10th Rugby World Cup matches, joining only three other Romanians to reach double figures. Romania coach Romeo Gontineac holds the record with 14.
"We can't be happy with that match, especially the first half," said Gontineac. "We were not in the game. We were not there ... when you have to defend all the time."
Scotland also started quickly against Romania, scoring two early tries, before Romania took the lead late in the game. On Saturday, the Romanians had their usual early problems but never looked in the match.
"It's a collective problem," he said. "It's true, we started badly against Scotland and we started badly against Argentina. It's up to us to be aggressive."
The only positives that Gontineac could see: Cazan's "nice try" and "we defended very well in the second half, despite being down a man for a time."
Argentina 43 (Santiago Fernandez, Juan Manuel Leguizamon, Juan Figalo, Lucas Gonzalez Amorosino, Juan Jose Imhoff, Genaro Fessia tries; Rodriguez 5 conversions, penalty), Romania 8 (Ionel Cazan try; Tiberius Ionut Dimofte penalty). HT: 26-8.
Follow Dennis Passa on Twitter: http://twitter.com/DennisPassa