Jenni Asserholt deflected a shot into the net for a first-period goal and Sweden held on to beat Japan 1-0 on Sunday in their opening game of the Sochi Olympics women's hockey tournament.
Valentina Wallner stopped 19 shots for the Swedes.
Nana Fujimoto made 22 saves for Japan, which had not qualified for the Olympics in women's hockey since the sport was added to the Winter Games in Nagano in 1998.
Sweden is the only team other than the United States or Canada to have reached an Olympic gold medal game, beating the Americans in the 2006 semifinal and earning a silver. But the Swedes have struggled lately, falling into the second-tier Group B that will have to compete for two spots in the quarterfinals.