And the 70-cap Toulouse veteran will be desperate to make his mark against Ireland, having been on the winning side in six of his seven matches against them.
Perpignan centre Mermoz, who was forced off in the 45th minute of France's opening encounter, will have to undergo an operation after suffering ligament damage.
It's the latest in a string of shoulder injuries for the 24-year-old who seems certain to miss the rest of the season and with it the World Cup in New Zealand.
"It's the real black spot on the evening," said the under-pressure Lièvremont.
"We now have several options.
"We can make a man-for-man change and bring in Yannick for Maxime or we could go with the backline which finished the game against Scotland."
Meanwhile replacement prop Luc Ducalcon looks set to drop out of the squad in favour of Biarritz prop Sylvain Marconnet.
The 27-year-old Castres man played the last half hour against the Scots but Marconnet has been brought in for his greater experience.
"Luc is still learning but he did some good things after coming on," said Lièvremont.
"But Sylvain's experience could be invaluable in what should be a more physical match."