The Six Nations match between France and Ireland in Paris has been postponed due to fears over the coronavirus.
Ireland were due to face their Championship-chasing rivals at the Stade de France on Saturday.
No new date has yet been announced, with French authorities banning gatherings of more than 1,000 people.
"The Six Nations match between France and Ireland will be postponed in agreement with the French Rugby Federation and tournament organisers," French sports minister Roxana Maracineanu said.
It has not yet been confirmed whether the women's and U20 matches against France this weekend will go ahead.
With Italy's match against England also called off, Wales' clash with Scotland is the only match scheduled for this weekend.
Ireland's game against Italy was also postponed last week, meaning Andy Farrell's men have only played four of their six matches in the tournament, and have not played since the chastening defeat to England in February.
"We're disappointed that it's not going ahead but at the same time we fully understand," Farrell said.
It is possible that the remaining fixtures will not be fulfilled until the autumn.
In club rugby news, European Professional Club Rugby has confirmed that the Heineken Champions Cup quarter-finals will proceed "as scheduled" next month.