Japan head coach Jamie Joseph has supported claims from prop Yusuke Kizu that Ireland scrummage illegally, ahead of their World Cup Pool A game in Shizuoka on Saturday.
Kizu has claimed that Ireland prop Cian Healy "steps out" and scrummages in at an illegal angle.
Ireland head coach Joe Schmidt insisted his side have one of the least penalised scrums in the Test arena as he replied to Kizu's claim.
But after Japan had named their team, which saw squad captain Michael Leitch's demotion to the bench, Brave Blossoms boss Joseph agreed that "at times they are illegal" in the scrum.
"I think first thing, Kizu is a young man, probably his first media experience, so that would be the first thing around Kizusan," said Joseph.
"We're coming up against a very strong scrum. Yes, at times they are illegal, but at all times they are a very strong scrum.
"We know that's a difficult part of the game, but we've really improved our scrum and lineout recently and it's an area we've been focusing on all week."
Hosts Japan beat Russia 30-10 in Tokyo on Friday to kick-off the first World Cup in Asia but the players admitted they had been overawed by the occasion in a largely uninspiring performance.
Joseph admitted Japan will need "the game of their lives" to beat Ireland and insisted skipper Leitch still has a big role to play, despite not starting against the No 1 ranked side in the world.
Pieter Labuschagne will captain Japan, with Joseph backing Leitch to have an impact off the bench.
"What I believe around the game, in terms of our bench, we've got to have an impact," added Joseph.
"If we're going to be in a position to win the match, it's going to come down to the last five or 10 minutes and we'll need clear leadership.
"Michael has had an injury all year, he's only played four or five games, and he's a very key player. But we have a lot of quality loose forwards and in-form players.
"It's a huge game for us and these players will need to play the best game of their lives; that's what they'll need to be successful on Saturday."
Joseph is targeting a place in the quarter-finals of the World Cup for the first time as part of the legacy of Japan hosting the tournament.
"In terms of legacy for the tournament, on our goals, as a team we want to do something we've never done before and that's make the top eight," he said.
"That will leave a legacy for rugby in Japan, but the quality of our play and how we conduct ourselves as a team is also important."
Japan: 15 Ryohei Yamanaka, 14 Kotaro Matsushima, 13 Timothy Lafaele, 12 Ryoto Nakamura, 11 William Tupou, 10 Yu Tamura, Yutaka Nagare; 1 Keita Inagaki, 2 Shota Horie, 3 Koo Ji-won, 4 Luke Thompson, 5 James Moore, 6 Kazuki Himeno, 7 Pieter Labuschagne (capt), 8 Amanaki Mafi.
Replacements: 16 Atsushi Sakate, 17 Isileli Nakajima, 18 Asaeli Ai Valu, 19 Wimpie Van Der Walt, 20 Michael Leitch, 21 Fumiaki Tanaka, 22 Rikiya Matsuda, 23 Lomano Lemeki.