12 Dec, 14:42
Prop Cian Healy is expected to miss the start of the 2014 RBS 6 Nations after undergoing surgery on his injured ankle on Wednesday.
Ian Keatley will wear the number 10 jersey in O'Gara's absence, as he did for the bonus point victory at home to Edinburgh back in October.
That is the only change head coach Rob Penney has made to the team that started the 26-17 success at Murrayfield last Sunday afternoon.
However, both full-back Felix Jones (knee) and replacement hooker Mike Sherry (ankle) need to come through the training run - currently in progress - unscathed.
Sean Henry makes way for Sherry's return to the selected matchday squad, while JJ Hanrahan, a regular for the Munster 'A' side, will hope to come off the bench to win his sixth senior cap for the province.
Penney's charges, who are second in Pool 1 behind Saracens, know that a bonus point win over their French opponents will probably be enough to make sure they qualify as one of the two best runners-up.
Talking about the Edinburgh game and the squad's approach to the crunch clash with Racing, second row Donnacha Ryan said: "Obviously we had a lot of unforced errors (against Edinburgh), but the conditions were quite tricky and we tried to force the game.
"Towards the end we kind of got very loose and allowed them in for two tries but it just verified what we did earlier on in the game by taking our penalties first.
"Racing have a massive amount of depth in their squad. We started off very well over there (in October) and we tried to do things that we wouldn't have normally tried to do - obviously it backfired on us.
"So, we've got to be a lot smarter than the way we've played the first day and, I suppose, the way we've played the last couple of weeks.
"We've really got to focus on building a system and not doing silly stuff, not doing one-off runners and losing the ball in the breakdown. We have to tighten things up, to have more control when we have the ball in attack and make it count."
MUNSTER (v Racing Metro 92): Felix Jones; Doug Howlett (capt), Keith Earls, James Downey, Simon Zebo: Ian Keatley, Conor Murray; David Kilcoyne, Damien Varley, BJ Botha, Donncha O'Callaghan, Donnacha Ryan, Peter O'Mahony, Tommy O'Donnell, James Coughlan.
Replacements: Mike Sherry, Wian du Preez, John Ryan, Billy Holland, Paddy Butler, Duncan Williams, JJ Hanrahan, Casey Laulala.