Following Ireland's defeat against New Zealand, Ulster's hooker Rory Best and Leinster's wing Luke Fitzgerald have both been ruled out for six weeks due to injury.
Fitzgerald suffered a medial ligament injury to his left knee during the game and is out of Sunday's game against Argentina. The damage is to the same knee that he injured last November, but this is a new injury and to a different part of the knee.
Best is also ruled out of the game next weekend after suffering a fractured cheekbone. He will undergo surgery and it is expected that he will be unable to play for 6 weeks while the injury is healing.
Both players will miss the Round 3 and 4 games of the Heineken Cup against Clermont and Bath respectively but should be back for Rounds 5 and 6 in January.
Rob Kearney also injured his knee and has suffered cartilage damage. He will undergo exploratory surgery this week to further determine the extent of the injury and the period of recovery that he will need, but is certainly ruled out of the game against Argentina.