David Wallace sustained a knee injury in Ireland's warm up match with England on Saturday following a hard tackle from Manu Tuilagi.
The Ireland flanker will miss all of the World Cup, Heineken Cup Pool Stages and a significant part of the Celtic League Season. He received surgery to his seriously damaged knee ligaments on the evening of the injury and will be replaced by Leinster's Shane Jennings.
Ireland's 30-man squad flew out to New Zealand today ahead of next months world cup.
David Wallace will come as a big loss to Ireland's squad after he was stretchered off and looked in serious pain on Saturday.