France v Ireland
Chabal has played himself into the France team
Stade de France, Paris
Friday, 21 September
Kick-off: 2000 BST
Live coverage on BBC Radio 5live, Radio Ulster MW & the BBC Sport website
Sebastien Chabal will start in the second row for France in the must-win World Cup game with Ireland on Friday.
With France having lost their opening game to Argentina and Ireland having struggled past Georgia and Namibia, both sides know victory is essential.
Captain Raphael Ibanez has recovered from a throat injury, while centre Yannick Jauzion has been left out.
David Marty and Damien Traille will be the centres, while Serge Betsen replaces Yannick Nyanga on the flank.
Coach Bernard Laporte has also recalled prop Olivier Milloud and lock Jerome Thion for the Pool D clash in Paris.
Frederic Michalak continues at fly-half, while fellow number 10 David Skrela is still sidelined with an Achilles injury.
When Laporte named his World Cup squad Chabal was viewed as a back-up option at second row but the Sale Sharks player, who has become a folk hero in France, has now forced his way into the first-choice team.
Pool D is the most closely contested at the World Cup, with Argentina, France and Ireland all in the top six in the IRB world rankings.
After two games, Argentina and Ireland are level on nine points with Argentina topping the group on points difference, while France are third on six points.
If France lose on Friday they will not - bar a freak result which would see minnows Namibia beat Argentina - be able finish in the top two and so would be out of the tournament before it even reaches the knock-out stages.
Defeat would be nearly as disastrous for Ireland.
They may have won their opening two matches but they failed to score the expected bonus point as they struggled past Georgia and are yet to play Argentina.
In short, Friday's encounter at a sold-out Stade de France will be the most significant match in the World Cup so far.
France: Poitrenaud; Clerc, Marty, Traille, Heymans; Michalak, Elissalde; Milloud, Ibanez, De Villiers, Chabal, Thion, Betsen, Dusautoir, Bonnaire.
Replacements: Szarzewski, Poux, Nallet, Nyanga, Beauxis, Jauzion, Rougerie.