The Sunwolves proved they can hold their own in Super Rugby but failed to win their competition debut in a 26-13 defeat to South Africa's Lions on Saturday.

The Tokyo-based Sunwolves went into their first-ever match in the Southern Hemisphere's premier club tournament with doubts surrounding their ability to compete, after gathering as a squad for the first time less than a month ago and managing to sign only 10 members of Japan's 2015 Rugby World Cup squad.

But the Sunwolves gave a crowd of 19,814 at Prince Chichibu Memorial Ground hope for the season ahead with a credible performance against the Lions, with captain Shota Horie scoring the team's first-ever try and Samoan flyhalf Tusi Pisi kicking two penalties and a conversion.

"I suppose the big thing for me as a coach is that we can always handle losing if we know that our players have given everything," said Sunwolves coach Mark Hammett, who returned to Japan from his native New Zealand on Friday night following the death of his mother last week.

"We are very proud of the effort that has gone in in a very short time. I'm not just talking about the coaches and the players but everyone who has been involved to get us up and running."

The Sunwolves next have a bye week but must then dive headlong into a hectic schedule that sees them play five games in South Africa, two in Australia and three "home" games in Singapore this season.

"The result is frustrating but it's a long season," said Horie, the Top League's 2015-16 season MVP. "There is a lot we can take from this game. We have to talk about what we need to do and use it in the next game.

"They were much bigger than us in the scrum, but after two or three we were able to deal with it to some degree. We need more time to talk about it together. Hopefully we can make good use of these next two weeks."

Pisi kicked the Sunwolves into the lead with a penalty in the sixth minute, and the home side clung on when Lions flyhalf Elton Jantjies missed two attempts at goal.

But a 19th-minute drive by the Lions forwards ended with Robbie Coetzee scoring a try for the visitors, and the Sunwolves fell further behind when Courtnall Skosan streaked through a gap in the defense to touch down in the 35th minute.

A Pisi penalty reduced the deficit to six points going into halftime, but a Jaco Kriel try stretched the Lions' lead one minute after the restart.

Just when the game looked like turning into a rout, however, the Sunwolves gained a foothold. The home side repelled a series of Lions attacks, before Horie crashed over in the 60th minute to register the first try in Sunwolves history.

"I was lucky," said Horie, who has Super Rugby experience from a stint with the Rebels in 2013-14. "The ball just came to me. The team as a whole got me into that position, and all I had to do was finish it off.

"The crowd really helped us today. It felt like a home atmosphere, and that gave us courage and motivation. If the fans keep coming like this, it can only help us."

The home side's hopes of staging a famous comeback took a hit when Lionel Mapoe scored another try for the Lions in the 67th minute, but Hammett was nonetheless satisfied with his team's debut effort.

"It's really important that we continue to work on the things that went well but also the things that didn't go well," he said. "On attack we showed that we can keep up with the pace of the game. One of the big things we need to work on is to match the physicality of the teams. We're comfortable with the speed but we need to be more physical.

"We scrambled well. Perhaps the Lions should have scored more but that bravery is a real positive to work on."

The Sunwolves' next game in Tokyo is against the Rebels on March 19.