Donnacha Ryan moves from lock to blindside flanker and Peter O'Mahony, who wore the number 6 jersey against Castres, takes over on the openside from Ronan.
Otherwise it is a case of as you were in the starting line-up, but on the replacements bench there is a first time inclusion in a Heineken Cup matchday squad for former Ireland Under-20 international David O'Callaghan.
The ever reliable Mick O'Driscoll, with 196 Munster caps under his belt, makes his first appearance of the Heineken Cup campaign on the bench.
Full-back Denis Hurley, who has started all five of Munster's Pool 1 games to date, is hugely motivated to book a home draw for the province after they became the first team to qualify for the quarter-finals last weekend.
"This is a big one for us because, although we have qualified for the knockout stages, we have not yet got the home quarter-final we want," he admitted.
"We have to go to Northampton to get the win and a home quarter-final because playing at home is massively important for both our players and fans.
"They may not be able to qualify for the quarter-finals but we know they will come out fighting because they are a very proud club and there were only two points in it when we won at Thomond Park in the opening round."
Hurley added: "There has been some talk of us not playing well but still winning but I feel we have stood tall against all the teams we have played against and, at the end of it, winning games is the most important thing.
"We are in this strong position because we have won all five of our pool games and when we click we are a very dangerous side.
"It means we have qualified for the Heineken Cup quarter-finals for the 13th time and that is a great record because we take enormous pride in our game."
The Munster management and players flew out from Shannon Airport this morning on an Aer Arann charter flight bound for Luton Airport.
MUNSTER (v Northampton Saints): Denis Hurley; Johne Murphy, Keith Earls, Lifeimi Mafi, Simon Zebo; Ronan O'Gara, Conor Murray; Wian du Preez, Damien Varley, BJ Botha, Donncha O'Callaghan, Paul O'Connell (capt), Donnacha Ryan, Peter O'Mahony, James Coughlan.
Replacements: Denis Fogarty, Marcus Horan, Stephen Archer, Mick O'Driscoll, David O'Callaghan, Tomas O'Leary, Ian Keatley, Danny Barnes.