Last year's semi-finalists Canada will be without talisman Milos Raonic for their Davis Cup clash with Japan in Tokyo beginning Friday after he pulled out with an ankle injury.
The withdrawal of the world number 11 deals a severe blow to Canada's chances in the world group first-round tie at the bayside venue.
"This decision was very difficult to make but I believe in the players on our team and that they can get us the win," Raonic said in a statement Thursday.
"With a team scenario the most important part this week is to come out with a team win and I believe this is the best way to do it."
Raonic's absence will be a huge boost for Japan, led by world number 18 Kei Nishikori, who began the year in promising fashion at the Australian Open by pushing Rafael Nadal hard in a 7-6, 7-5, 7-6 fourth-round loss.
Peter Polansky and Frank Dancevic will carry Canada's hopes on the opening day, with Vasek Pospisil only passed fit for doubles.
Nishikori faces Polansky before Go Soeda takes on Dancevic in Friday's singles.
An inspired Nishikori helped Japan return to the Davis Cup world group with a 3-2 comeback victory over Colombia last September.
Japan hold a 5-0 record against Canada in Davis Cup competition, although they have not met for more than 75 years. Japan shut the Canadians out on grass in Montreal in 1938.
The winners of this weekend's tie will play either defending champions the Czech Republic or the Netherlands in the quarter-finals in April.