Two-time defending champions Argentina XV suffered their first loss in the three-year history of the Americas Pacific Challenge, losing 36-31 against a Samoan A side unrecognisable from the one that finished fourth in last year's competition.
In what was a good opening day for the Oceania representatives, Tonga A also recorded a 39-30 victory against last year's runners-up, the USA Select XV, while Uruguay A christened the new artificial pitch at their Estadio Charrua home with a 35-21 win against their Canadian counterparts.
Continuing the high-scoring tradition of APC matches, 192 points and 24 tries were scored across the three games, only marginally less than the nine-try average per game in 2017, as players from the competing nations looked to push their claims for senior rugby in time for Rugby World Cup 2019.
Argentina XV 31-36 Samoa A
In sunny conditions at the Estadio Cahrrua in Montevideo, Argentina XV finally lost their unbeaten record at the Americas Pacific Challenge.
Argentina XV had won all six of their previous matches at the key development tournament, including an 85-14 win over Samoa A 12 months ago, but they were well beaten here with the final scoreline not doing the Pacific Islanders justice.
Determined to put the record straight from last year, Samoa A got off to a storming start and, by the 20th minute, had already scored two tries. Miakele Tapili was the first to cross, the second-rower running down the right touchline and breaking through some feeble tackles before full-back Johnny Vaili collected a chip kick that caused mass confusion in the Argentinian ranks for the second.
Patrick Faapale's conversion was followed by two penalties from the boot of centre Alai Leuila as Samoa A raced into an 18-0 lead.
Argentina XV were given an invaluable lifeline when loose-head Rodney Tapu was sent to the sin-bin in the 23rd minute, the defending champions capitalising on their numerical advantage to score through full-back Bautista Daireaux. Winger Leopoldo Herrera added a second shortly after the Samoans were restored to their full complement of players and with Joaquin Bonilla converting both, the gap between the sides was down to just four points.
The second half was similar to the first, with Samoa playing the better rugby and adding points through Leuila's third penalty and a try from wing Johnny Samuelu who showed his aerial ability in claiming a high ball.
Argentina XV replied after another Leuila penalty, replacement hooker Axel Zapata touching down in the 65th-minute to bring the score back to 29-19 to the Islanders.
Six minutes later, Samoa A flanker Petelo Mapu made the game safe when he bumped off a tackle to finish from 15 metres, Leuila converting to take his points tally to 14 for the match.
Santiago Carreras and Santiago Portillo scored late tries as the Argentinians secured two bonus points.
Tonga A 39-30 USA Select XV
Tonga A scored twice in the last eight minutes to come from behind in an entertaining game in which the lead changed hands seven times.
After a quiet opening to the match, USA Select XV got the first points on the board when George Tu’ineau was sin-binned for a high tackle and Dylan Audsley kicked the subsequent penalty.
The first of two tries from lively scrum-half Sione Ika, converted by half-back partner Saia Fililava, momentarily put Tonga A in front but the Americans responded with a try for number eight Brendan Daly, converted by Audsley, who also nailed another three-pointer to make the score 13-7.
Then, it was the Tongans turn to take command. Second-rower Irwin Finau muscled his way over from close range with Fililava converting and adding his own penalty goal. The latter came after Psalm Wooching was shown yellow for a professional foul at the breakdown.
Despite being short-handed, it was the Americans who scored first after the break, regaining the lead when Tim Maupin finished off a simple two-on-one. Audlsey once again made no mistake from the tee.
The topsy-turvy nature of the game continued as Ika's second try, in the 54th minute, put Tonga A 22-20 up, but Vili Toluta’u's try and a conversion and penalty from Audsley saw the pendulum swing back to the USA Select XV.
Tonga A now found themselves two scores behind with 15 minutes remaining and the task ahead of them was made even more difficult when they lost number eight Takau Cocker to the bin within seconds of conceding their third try.
However, they responded in magnificent fashion with Sione Lave and Tevita Hafoka crossing in the 72nd and 74th minutes. Fililava converted both tries and added a late penalty to bring the curtain down on a breathless match.
Uruguay A 35-21 Canada A
With Los Teros having won twice earlier in the year, the Uruguayan A side seized the chance to complete a hat-trick of wins over the Canadians in 2018 in front of an enthusiastic crowd in Montevideo.
Lacking composure with ball in hand in attack, Uruguay A had to settle for two penalties from the boot of wing Federico Favaro in the early exchanges.
Doug Fraser got the first try of the match for Canada A on 34 minutes but it was the hosts who led at the break, 13-7, thanks to a penalty try.
Pat Parfrey's converted try handed Canada A the lead at the start of the second half but they were only in front for nine minutes after Favaro landed his third penalty.
Uruguay A's advantage was up to nine points when scrum-half Santiago Arata used his electric turn of pace to scamper over.
There was a glimmer of hope for last year's bottom team when Gordon McRorie scored a brilliant solo effort, but Uruguay A closed the door on any hopes Canada A had of a comeback win when Manuel Diana and Leandro Leivas dotted down late on.