Tropical Storm Mitag could bring high winds and heavy rain to the southern Japanese island of Kyushu on Wednesday, when France play USA in Fukuoka, World Rugby said.
The IAAF said the forecast WetBulb Globe Temperature — a measure of the heat stress which combines temperature, humidity, wind speed and other factors — was expected to be 28 degrees Celsius at the new start time.
The Welsh were 23-8 ahead at half-time but they had to withstand a furious second-half onslaught when Australia fought back to within a point late in the game.
Coming off a 48-7 loss to Italy, the starstruck Canadians are braced for even bigger hiding by their All Blacks idols but at the same time they are relishing the opportunity just to be on the same paddock as three-times world champions.
South Africa famously went down to Japan in the 2015 World Cup's 'Miracle of Brighton', an upset the Brave Blossoms reprised with their 19-12 win over Ireland.
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.
Saturday's success was badly-needed by the Pumas, whose campaign in Pool C — the tournament's 'group of death' because it features three major sides — started with an agonising 23-21 loss to fellow heavyweights France.
The Boks, the overwhelming favourites in this match, opened the scoring in the 10th minute when Bongi Mbonambi crashed over the line from a driving maul.
