Zebo will be making his Heineken Cup debut on the day that vastly-experienced out-half Ronan O'Gara becomes only the second player to win 100 Heineken Cup caps - O'Gara's long-time provincial team-mate John Hayes was the first.
Will Chambers, who was used as a replacement against Castres, starts on this occasion, with the player he replaced that day, Danny Barnes, dropping to the bench
Otherwise the other changes are positional, Johne Murphy donning Howlett's number 14 jersey and Denis Hurley staying at full-back where he has impressed in the most recent games against Edinburgh and Ospreys.
While acknowledging the Scarlets' strength behind the scrum, the province's captain Paul O'Connell has also noted the improvements they have made up front.
"Obviously you have guys like (Rhys) Priestland, (Jonathan) Davies and (George) North which will give us something to focus on, they were probably the stars for Wales in the World Cup," he said.
"But they did really well in the scrum against Northampton, they have a good lineout and they've been playing as a unit now for a while.
"The World Cup hasn't disrupted them that much, they don't have to rest players (as decreed by the Welsh Rugby Union), so they've been playing together quite a bit and they've done really well up front.
"Simon Easterby is involved with them and he's a guy we would know well. I would have had great respect for Simon as a player, I know what he is made up of and he is mentally very strong.
"He will look to have instilled that in the Scarlets players. They're a very good forward unit - any team that can go away to Northampton, win well and pick up a bonus point has to have a serious pack."
MUNSTER (v Scarlets): Denis Hurley; Johne Murphy, Will Chambers, Lifeimi Mafi, Simon Zebo; Ronan O'Gara, Conor Murray; Wian du Preez, Damien Varley, BJ Botha, Donnacha Ryan, Paul O'Connell (capt), Peter O'Mahony, Niall Ronan, James Coughlan.
Replacements: Denis Fogarty, Marcus Horan, John Hayes, Donncha O'Callaghan, Denis Leamy, Tomas O'Leary, Ian Keatley, Danny Barnes.