Jason Jenkins' Munster debut will have to wait after he suffered a setback in training this week.
Described as good to go by Reds forward coach Graham Rowntree on Wednesday, the versatile South African was in line for his first appearance for the province having returned to fitness.
But he subsequently suffered a thigh injury in training and the lock/back row is awaiting a scan.
The Reds, who make 11 changes for Sunday's clash at the Scarlets (2pm), are also without Rowan Osborne (concussion) and Kenyan Knox (low-grade hip injury).
After winning their first two games at home, Munster will be without big name players such as Peter O'Mahony, Joey Carbery, Simon Zebo - who was only on the bench against the Stormers last weekend - Gavin Coombes and Dave Kilcoyne.
That's apart from the still to return Conor Murray, Tadhg Beirne and Damien de Allende after their summer Test commitments - as Johann van Graan makes good on his promise to keep rotating his squad.
RG Synman remains on the bench after his first two appearances as a sub following long-term injury, while Ben Healy will be at out-half and partnered by Neil Cronin.
In-form Jack O'Donoghue skippers Munster, who feature an exciting young all-Irish second row in Thomas Aherne and Fineen Wycherley.
Leinster, meanwhile, continue to rest Johnny Sexton as Zebre visit the RDS Arena on Saturday (2pm).
Luke McGrath will skipper the Blues, who have also won their opening two URC fixtures, as winger Adam Byrne makes his first start in 22 months following serious injury problems.
On the other flank, Jordan Larmour makes his first start, too, after returning from injury.
Harry Byrne also returns having returned to full fitness and replaces his brother, Ross, at out-half, while flankers Dan Leavy and Scott Penny making their first starts of the season, as does Devin Toner in the second row.
The Blues will also have a new centre combination in place against the Italians, with Ciaran Frawley partnering Jamie Osborne, and hooker Ronan Kelleher is on the bench after his Lions experience in the summer.
Connacht have made three changes for Saturday's Sportsground clash with the Dragons at the Sportsground (5.15pm).
Matthew Burke, Paul Boyle and Ben O’Donnell are come in - O'Donnell into the back three, Burke into the front row and Boyle will wear the no 8 jersey.
Munster : Nash, L Coombes, Goggin, Daly, Healy, Cronin; J Loughman, D Barron, Archer; Ahern, F Wycherley, O’Donoghue, Cloete, O’Sullivan.
Leinster : J O'Brien, A Byrne, Osborne, Frawley, Larmour, H Byrne, McGrath; E Byrne, Cronin, Ala'alatoa, Toner, Baird, Leavy, Penny, Ruddock.
Connacht : O'Halloran, O'Donnell, Farrell, Daly, Hansen, Carty, Marmion; Burke, Heffernan, Bealham, Dowling, Dillane, Prendergast, Butler, Boyle.
