A thrillingly close encounter for 60 minutes, Argentina’s class eventually told as they put five tries past Tonga to ensure they advance to the knockout phase of a third consecutive World Cup.
The Pumas found themselves in a real battle against the tier two nation, but 30 points from inspirational fly-half Nicolas Sanchez sent them on their way to a resounding victory.
With a plucky Namibia side still to play, Argentina will be confident of storming into the quarter finals.
Leicester was treated to a feast of rugby, with seven tries scored in a match which ebbed and flowed up until the hour mark. Tonga will consider themselves unlucky not to come away with anything from a great display, but Argentina were good value for the bonus point win in the end.
A physical start saw both sides lucky to not each have a player sent to the bin, with referee Jaco Peyper giving the game a chance by just warning both sides to avoid tackles around the neck.
Tonga broke the deadlock on seven minutes with the first threatening spell of the match from either side. Argentina crumbled in defence to allow fly-half Kurt Morath to score the opening try of the game, which he then failed to convert.
The men in red continued to look dangerous and scrumhalf Sonatane Takulua was unfortunate to knock the ball forward just metres out from the Argentine try line.
Nicolas Sanchez finally registered Argentina on the scoreboard with a penalty on 18 minutes, giving them a foothold in a match dominated by the Pacific Nation in the early stages.
The South Americans finally exploded into life less than two minutes later, with fullback Joaquin Tuculet finishing off a well-worked team move.
A second try came almost immediately from the restart, and a mazy Santiago Cordero run from his own half laid the foundations for opposite wing Juan Imhoff to step inside and touchdown.
The pendulum had certainly swung the way of the Pumas, and Sanchez nudged them 15 points ahead on 27 minutes from the tee.
Morath returned the favour by reducing Tonga’s arrears back to 12 points, with seven minutes remaining of a half that felt like it flown by.
Tuculet and Imhoff combined down the left wing but with just one man to beat, the fullback’s chip over bounced into touch and the chance of a third try went begging.
It was Tonga that finished the half strongest however, with great work from wing Telusa Veainu to set up big prop Soane Tonga’uhia for a well worked second try for the Pacific nation, and make it a seven point game at the break.
Tonga continued to chip away at the Argentine lead with a Morath penalty reducing the gap four with another clinical penalty with the half less than two minutes old. However Sanchez responded almost instantaneously to reinstate their one converted try lead.
A big heave from Tonga won them another penalty, this time from an Argentina put in a the scrum. Morath was unable to make it count however, letting Argentina off the hook with his second miss of the afternoon.
Pressure continued to mount from Tonga regardless, and Argentina were perhaps fortunate not to be a man down with Tomas Lavanini sancitoned with only a penalty after barging into Sione Piukala with no arms in the tackle.
Again, Morath failed to convert his penalty, but Sanchez made no mistake with a long range effort moments later as he exerted his dominance in that personal duel.
The Argentina ace missed his first kick on 55 minutes, but he came close to a try on the hour mark. Recycled ball was bundled over the line underneath the posts by Lavanini, but the TMO indicated that the ball was clearly held up.
Sanchez did register a try that his mercurial play had deserved on 64 minutes, finding a gaping hole in the Tongan back line to stride through for his second World Cup try.
After a raft of changes for both sides, Tonga once again threatened to fight back. With eight minutes to go however, The Pumas struck the killer blow with substitute Julian Montoya just avoiding touch to score the bonus try.
Despite the best efforts of Tonga in the dying minutes, the lead proved to be unassailable, and Argentina closed the match with a fifth try through Cordero.
What comes next for both
Argentina now have one foot in the quarter-finals, as second place now looks all but assured with Namibia their opposition in their final Pool clash.
The Pumas could still technically top the group, but it is hard to imagine a scenario where Tonga are able to defeat New Zealand. With a meeting with either Ireland or France likely in the next round, the South Americans will need to tighten up defensively if they are to progress any further.
Tonga now face the All Blacks in their final Pool game, and risk not even finishing third, with Georgia rounding off their campaign against Namibia.
Man of the match: Nicolas Sanchez
The mercurial Number 10 was almost flawless for Argentina, missing just two tricky kicks throughout the match. A brilliant individual try was the icing on the cake of a 30 point haul, which inspired the Pumas to a healthy victory in the end.
Argentina: 15. Joaquin Tuculet, 14. Santiago Cordero, 13. Matias Moroni (Santiago Gonzalez Iglesias 70), 12. Jeronimo De La Fuente, 11. Juan Imhoff (Horacio Agulla 58), 10. Nicolas Sanchez, 9. Martin Landajo (Tomas Cubelli 65), 8. Leonardo Senatore (Facundo Isa 51), 7. Juan Martin Fernandez Lobbe, 6. Pablo Matera, 5. Tomas Lavanini, 4. Guido Petti (Matias Alemanno 65), 3. Ramiro Herrera (Juan Pablo Orlandi 65), 2. Agustin Creevy (Julian Montoya 65), 1. Marcos Ayerza (Lucas Noguera 65)
Tonga: 15. Vungakoto Lilo (David Halaifonua 70), 14. Telusa Veainu, 13. Siale Piutau, 12. Sione Piukala (Latiume Fosita 50), 11. Fetu’u Vainikolo, 10. Kurt Morath, 9. Sonatane Takulua (Samisoni Fisilau 70), 8. Viliami Ma’afu (Opeti Fonua 60), 7. Nili Latu, 6. Sione Kalamafoni, 5. Joseph Tuineau (Sitiveni Mafi 67), 4. Tukulua Lokotui, 3. Halani ‘Aulika (Sila Puafisi 70), 2. Elvis Taione (Aleki Lutui 60), 1. Soane Tonga’uiha (Sona Taumalolo 60)