The more fancied Argentina capitalised on some Tongan handling errors in the first half to race to a quick lead and resisted a brave fight-back from the underdogs in an entertaining match at the Hanazono Rugby Stadium.
The three-times world champions have beaten Canada comfortably in the three times they've met in previous World Cups and whipped Namibia 58-14 when they met for the only time at London's Olympic Stadium four years ago.
Magnus Bradbury, Jamie Ritchie and Blade Thomson come in for John Barclay, Ryan Wilson and flanker Hamish Watson, who has flown home after a tournament-ending injury.
In a shock result that rivals their "miracle of Brighton" defeat of South Africa at the 2015 tournament, the Brave Blossoms took the lead through a Kenki Fukuoka try halfway through the second half and hung on desperately with a courageous defensive effort.
The flying winger scored a sizzling treble as the host nation beat Russia 30-10 in last week's Pool A opener, prompting gushing praise from Japan coach Jamie Joseph.
Welcome to this week’s episode of EWN Sport Fantasy Football podcast, where we learn that anything can happen – and it usually does.
Dane Haylett-Petty starts in place of Kurtley Beale at fullback and there was no room in the matchday 23 for Christian Lealiifano, Australia's starting fly-half in the 39-21 win over Fiji.
Springbok Women's captain Babalwa Latsha says they are determined to improve on their performance against Scotland as they look to get their two-match series off to a winning start at the City Park Stadium in Cape Town on Monday.
It promises to be a bumper summer of cricket with the Mzansi Super League, England and Australia tours, the under-19 World Cup and the T20 Women's World Cup next year all on the schedule.
South Africa and Namibia clash in an 'African Derby' at the Rugby World Cup, with both sides looking to bounce back from opening game losses.
