Out-half Ronan O'Gara has a dead leg and is also unable to train, so the uncapped Leinster back Ian Madigan joins the squad.
Scrum half Paul Marshall comes into the squad in place of Eoin Reddan who was unable to play in Leinster's league clash with Edinburgh due to a leg injury.
Prop Ronan Loughney comes into the squad in place of Declan Fitzpatrick, who is continuing rehab on a knee injury in Ulster.
Second row Mike McCarthy picked up a calf knock during Connacht's encounter with Glasgow Warriors and is replaced by Leinster second row Devin Toner.
The final change is Simon Zebo, who turned an ankle during Munster's victory over the Dragons and is unable to train. Craig Gilroy replaces him in the training squad.