Speculation is mounting that Cian Healy is struggling in his race to be fit in time for the World Cup.
The loosehead prop underwent neck surgery to repair a disc in May and there are growing fears that he will not recover before Joe Schmidt names his 31-man squad.
Healy has also had surgeries on his hamstring and ankle in the last two seasons, and it is understood that the recovery time on his neck is taking longer than anticipated.
Earlier this month, Healy confirmed that he was back in Ireland camp but admitted that the injury had given him a real scare.
"If it's a neck surgery and it could have left me paralysed and it might if I didn't get it fixed and that's the way my head thinks," he said.
"They assured me that it wasn't a situation like that. I was happy to be told that I'd be able to play rugby again."
Meanwhile, Leinster are set to announce the signing of scrum-half Conrad Hoffmann on a three-month contract, according to reports in South Africa.
With Eoin Reddan and Isaac Boss expected to be named in Schmidt's World Cup squad, Leinster have been searching for a scrum-half to bolster their options during that period.
Hoffmann is currently with Super Rugby outfit the Sharks but will not feature in the team's upcoming Currie Cup campaign and will instead link up with Leinster.
The 27-year old is uncapped at international level but was included in the Junior Boks squad who competed at the Junior World Cup in 2006.
Hoffmann has played for five different Super Rugby sides, including Western Province where he was a team-mate of Ireland back-row Robbie Diack, making 44 appearances and scoring 67 points.
He will provide competition for Luke McGrath during the World Cup period.
Elsewhere, Australia's Michael Hooper will appear before a disciplinary hearing tomorrow after being cited for alleged foul play.
The flanker is alleged to have struck Pumas out-half Nicolás Sánchez in an incident off the ball in the Wallabies' win on Saturday evening.
If found guilty, Hooper is likely to miss Australia's Rugby Championship title decider against New Zealand next month.
Australia coach Michael Cheika has also confirmed that no further action will be taken against Quade Cooper for his foul-mouthed tweet which he has since deleted and apologised for.