Johnny Sexton did not train with the Irish rugby squad today ahead of Saturday's World Cup Pool A game against Japan in Shizuoka.
The fly-half sustained a leg injury in Sunday's opening win over Scotland.
The coaching staff hope Sexton will resume training on Thursday.
Ireland skills coach Richie Murphy said: "Johnny went through rehab today, but he had also done some work with the team. But he's being monitored.
"We expect him to train fully on Thursday. That wouldn't be unusual for him not to train two days after a Test match."
Robbie Henshaw is back running as he recovers from a hamstring injury, while Bundee Aki and Peter O'Mahony have passed their Head Injury Assessments in full.
"Robbie was in training today, he's in his return-to-play phase now," said Murphy.
Keith Earls, Rob Kearney and Munster 10 Joey Carbery are all also fit and available for Saturday's match.
Murphy added: "They were all at the point at the end of last week where they were effectively ready, but we didn't want to take any risks."
In Pool A this morning, Russia and Samoa meet at 11.15am in Kumagaya.
CJ Stander during a gym session at the Yumeria Sports Grounds in Iwata, Shizuoka Prefecture, Japan. Pic: Brendan Moran/Sportsfile
