The Ireland international will be sidelined for a number of weeks, leaving Casey Laulala and James Downey poised to start together in the centre in Paris.
South African prop Wian du Preez suffered a knee injury in the game against Leinster and will see a specialist tomorrow to determine the timeframe for his absence.
Flanker Niall Ronan, who was a late withdrawal from the squad to face Leinster, did train today at Cork IT but did not take a full part in the session. He is unlikely to be in consideration for the Racing Metro game.
Meanwhile Felix Jones will return to action at some level this weekend. He took a full part in the Munster squad's training session this morning.
Munster kick off their 18th Heineken Cup campaign with a trip to the Stade de France to face Racing Metro. Pool 1 also includes the Michael Bradley-coached Edinburgh and Mark McCall's Saracens side.
Commenting on the province's opponents, Munster head coach Rob Penney said: "It's a tough pool with a difficult start. I'm not looking at the topsy-turvy start that Racing Metro have made to their Top 14 campaign.
"They will be more dangerous because of their unpredictability. When the big games come along their big name players start firing, and they've got a lot of them."
The New Zealander added: "Being able to coach in the Heineken Cup was one of the major attractions of coming to Munster. It is the best club rugby tournament in the world game.
"It allows you to pit yourself against some of the best coaches around and the wealth and depth of talent available to the teams is incredible. There is so much passion associated with the competition and I can't wait to get going."