Japan won its Davis Cup World Group tie on Sunday, clinching a quarterfinal berth when Frank Dancevic of Canada was forced to retire in the second set of his reverse singles match with Kei Nishikori.
With Nishikori leading 6-2, 1-0, Dancevic withdrew with a stomach injury giving Japan an insurmountable 3-1 lead.
"I pulled a stomach muscle," Dancevic said. "I hurt it in a serve in the second set and there was no way I could continue against a player like Kei."
It was the latest in a series of injuries for the Canadians. Milos Raonic pulled out with a left-foot injury on Thursday while Vasek Pospisil, who was originally slated to play doubles on Saturday, was unable to recover in time from an injury.
Nishikori, who is No. 18 in the world rankings, won both his singles matches and also played in Japan's doubles win on Saturday.
"The pressure is always on me to win both singles matches," Nishikori said. "This time I was able to help win three matches."
Japan improved to 6-0 against Canada in Davis Cup play. The two countries last met in 1938. Japan advances to the quarterfinal round for the first time and will face either the Czech Republic or the Netherlands.
Go Soeda beat Peter Polansky 6-1, 6-4 in the dead rubber to widen the lead to 4-1.