But on the Scandinavians' second power play Eliasson produced another slapshot which Asserholt tipped past Nana Fujimoto to open the scoring on 12:38. It was a deserved lead for Sweden, and a deserved assist for Eliasson, an eye-catching blue-liner with a powerful shot.

"I thought we had a good power play today," said Asserholt. "It's been struggling a bit this season but now it's working and that's good. And scoring a goal is a great feeling. It doesn't matter who scores but it's nice to get one early in the tournament. Hopefully we can do more with that."

Japan struggled a little to carve out chances early, but Sakagami - now reunited with her stick - might have grabbed an instant equalizer when a rebound dropped kindly for her. However, those nerves kicked in again and she snatched at the chance and fired well wide of Valentina Wallner's goal.

Sweden dominated the early stages of the second period, with Pernilla Winberg producing a fine surge down the left before drawing a good block from Fujimoto among the highlights. But the Japanese gradually came into the game more, and produced two good chances in the closing minutes of the session.

First a Swedish penalty set up huge pressure on Wallner's net with the goalie struggling to swat Chiho Osawa's shot round the post after it came through a crowd of players. Then Japan came closer still, with Wallner beaten as Hanae Kubo hit the piping.

Sweden survived those scares to take a slender advantage into the interval, but the momentum of the game had shifted. Japan had the edge in the third, and Kubo, Japan's record goalscorer, was proving a constant threat. She perhaps should have added to her 28 international goals in the 49th minute when she found herself in open ice in front of goal but flashed her shot wide of the target. Roared on by most of a crowd of just under 3,000 in the Shayba arena, Japan tried desperately to tie the game and claim its first Olympic tournament point but Sweden did enough to calm the storm and sneak a hard-fought first win.

Japan's assistant captain Yuka Hirano was proud of her team's efforts despit the result: "Our speed resulted in self-confidence on our part. We’re really sorry we weren’t able to score, but we tried hard. I had a chance to carry the puck quite a lot, but unfortunately it didn’t result in any goals for us. Anyway, we’ll learn our lesson and we’ll go on from here."

Assistant captain Erika Grahm admitted that things had been tough but insisted that Sweden had been ready for the game. "We already discussed about how Japan was energetic and sharp so we weren't all that surprised about it.

"Japan had some good counter attacks, but we were able to keep an eye on what they were doing."

Sweden moves on to play Germany next, looking for a second win to take the initiative into a potential Group B decider against Russia, and forward Winberg is expecting another tough encounter. "That’s going to be a tough game as well. It’s the Olympics and everyone has their best team. They’re going to play their best. We’re just going to focus on our game and work on our details." Japan, meanwhile, prepares to face the hosts on Tuesday.