Tokyo - Rugby World Cup organisers warned on Monday that a powerful typhoon forming to the south of Japan could bring fierce winds and torrential rain over the last weekend of the pool stages.
Japan's Meteorological Agency (JMA) is tracking Typhoon Hagibis, expected to develop into the highest level of "violent", which is due to start hitting the southern island of Kyushu around October 12.
"We have not issued any warning yet as it is still far from the Japanese archipelago. But it could be the strongest to hit Japan this year," a JMA official told AFP.
There are two World Cup fixtures on the island at that time - a potentially critical Pool A Ireland-Samoa clash in Fukuoka on October 12 and Wales-Uruguay in Pool D in Kumamoto on October 13.
The latest information from the Rugby World Cup weather advisors is that "the typhoon is tracking in a north-westerly direction and could bring high winds and heavy rain to southern Japan on October 12 and 13", organisers said in a statement.
They said it was "too early" to assess the exact trajectory of the storm and whether it would impact the game, but stressed they had a "robust contingency programme" in place if the games were affected.
Games can be moved to a different venue if it looks like a typhoon will prevent them from being played.
However, if a match during the pool phase has to be cancelled, it counts as a 0-0 draw.
This could prove costly to Ireland, who are in a fierce three-way battle with Japan and Scotland for a quarter-final place and would be expected to beat Samoa with relative ease.
Wales will qualify for the last eight if they beat Fiji on Wednesday but a draw against Uruguay could jeopardise their ability to top their pool.