Taking Kaoru Mitoma to the Asian Cup had been "a risk", Japan's coach Hajime Moriyasu said Thursday, with the injured Brighton winger yet to play and no timescale for his return.
Japan have reached the last 16 in Qatar and a possible showdown with South Korea but Mitoma has not made any of their three match-day squads so far.
The 26-year-old has not played at all since hurting his ankle in a 1-1 draw with Crystal Palace on December 21.
Moriyasu said Mitoma's recovery was "coming along as expected" but will not rush him back or put a date on his return.
"I called him up when he was injured and we didn't know what was going to happen at first, so it was maybe a risk," he said, calling Mitoma "a potent weapon".
"I don't want to use him until he's ready. I wanted to use him in the third game but it wasn't possible.
"He has been training more but I didn't want to push it with him."
Brighton coach Roberto De Zerbi has said he was "really surprised" that Moriyasu included Mitoma in his squad, claiming club doctors told him the player needed four to six weeks to recover.
Moriyasu said Japan had been in regular communication with Brighton about Mitoma's injury, and suggested De Zerbi was playing to the gallery.
"I think the coach said that on purpose in front of the media," said Moriyasu.
"We had been in touch with them and had constant updates on his fitness.
"There was no way we weren't communicating with them."
Japan were pre-tournament favourites but their progress to the knockout rounds in Qatar has not been smooth.
They were stunned 2-1 by Iraq in their second game and did not keep a clean sheet in any of their three group matches.
Moriyasu said Mitoma gives them "more variety and power", but believes other players in his squad can fill the winger's boots.
"Our opponents know who Mitoma is and they know his reputation and that puts them under pressure," he said.
"At the same time, we can't be a team that can't win when Mitoma isn't there."
