Mathieu Bastareaud will miss France's RBS 6 Nations clash with Ireland due to concussion.
The juggernaut centre has been ruled out of Saturday's Aviva Stadium encounter just days after being drafted back into Les Bleus' squad.
The 28-year-old Toulon star has terrorised Ireland's midfield in the past with his bullish ball-carrying, but has failed to prove his fitness so must sit out the weekend battle in Dublin.
"Following a concussion Mathieu Bastareaud underwent a neurological test which does not allow him to be available for Ireland v France," the French Rugby Federation tweeted.
Ireland hope to have British and Irish Lions fly-half Johnny Sexton fit after calf trouble for his first taste of the Six Nations this term.
France have continually targeted the Leinster playmaker in previous contests by sending freight-train centre Bastareaud down his channel in a bid to unsettle the 31-year-old.
Sexton claimed two tries and suffered a suspected knockout blow when Ireland toppled France 22-20 in Paris to claim the Six Nations title in 2014, in Brian O'Driscoll's fairytale Test farewell.
Then Sexton suffered a nasty black eye when Ireland again edged out Les Bleus in Dublin in the 2015 tournament.
The French then increased the bad blood by openly vowing to target Sexton in the World Cup 2015 clash, though Ireland again prevailed, this time 24-9.
While Sexton has long-since proved he can and will stand firm amid such roughhousing tactics, Ireland may just breathe a sigh of relief that Bastareaud cannot set his sights on hugely-gifted but inexperienced centre Garry Ringrose.
France have also lost Clermont flanker Damien Chouly to an ankle injury, with Stade Francais' Raphael Lakafia called up as a replacement.
Guy Noves' side have switched their training camp from Paris to Nice this week, in a bid to take advantage of warmer climes.
France are already steeling themselves for a sizeable set-piece battle in Dublin this weekend.
"It is certainly a change from Marcoussis, but we are working in the same spirit and with the same motivation," said lock Paul Jedrasiak.
"In the evening we stay in the hotel and focus on the match. It will be one heck of a battle in Ireland.
"It will be especially feisty in the lineouts and scrums."
Hooker Camille Chat echoed Jedrasiak's sentiments, adding: "Ireland have a huge scrum.
"We've been working hard on the lineouts. It is imperative to be more precise in certain phases of the game and to be good in the tackle."
Source: PA
