Jack Conan is facing an extended period on the sidelines after undergoing surgery on his fractured foot.
The Leinster back-row replaced Peter O'Mahony in Ireland's opening World Cup win over Scotland before a training-ground injury ended his tournament prematurely.
"Jack is going to have some sort of procedure done so we'll have some more information later in the week," Leinster head coach Leo Cullen confirmed today.
Conan is believed to be a doubt for all of the province's Champions Cup fixtures and possibly the 2020 Six Nations.
Prop Ed Byrne also remains unavailable as according to Cullen his recovery from a neck injury has been "a bit slower than we thought".
"The break next week and hopefully he'll be good to go after that. But, again, we can't say for certain."
Meanwhile, Munster flanker Chris Cloete has been released from the province's touring party after injuring his ankle in last weekend's win over Southern Kings.
The South African will miss Munster's second fixture in his homeland, Friday's meeting with Cheetahs in Bloemfontein.
Follow Ireland v Samoa on Saturday 12 October (kick-off 11.45am) via the live blog on RTÉ.ie/Sport and the News Now App, watch live on RTÉ2 or listen to live match commentary on RTÉ 2fm.