Japan warmed up on Saturday for their World Cup opener against Chile without skipper Kazuki Himeno as assistant coach Tony Brown admitted to pre-game nerves.
Captain Himeno missed the 'captain's run', the traditional eve-of-match training session, at Toulouse Stadium.
"He has got a bit of a calf problem, but we hope he will come right in time for the game," said Brown. "We won't know until the morning."
Japan kick off against World Cup debutants Chile in Pool D on Sunday.
Brown anticipated first-night anxiety for both sides.
"Every player at a World Cup is under pressure. The All Blacks and France last night, players who are super experienced at test-match level, playing their first game at the World Cup, there were nerves in that game," he said.
"There will be nerves tomorrow. It's how we deal with that as a team. Chile playing their first World Cup will be nervous as well."
"It's an exciting time for the players at a World Cup and 100 per cent they are going to be nervous, but the best rugby players in the world get nervous before a game. It's the same for everyone."
Brown said Japan have been working on improving their play without the ball.
"Four years ago in Japan we played some amazing rugby," he told reporters.
"Hopefully we can add stronger defence, more of a kicking game and pressure to our attack, which is always Japan's point of difference.
"Chile have got some dangerous players so we are going to have to shut them down with our defence.
"I feel that if we can play our style of rugby, which is fast and skilful, then we are going to create a lot of opportunities."
The biggest threat when Japan reached the quarterfinals four years ago was Kotaro Matsushima, who scored five tries from the wing.
He will start there again on Sunday despite often lining up at full-back since the last World Cup.
"For the game against Chile we want to put him on the wing as we feel he is a world-class winger," said Brown.