Ireland full-back Rob Kearney will miss the November internationals as he requires surgery on a troublesome back injury.
The Leinster stalwart, who has started Ireland's last 12 Tests, could be sidelined for up to 10 weeks.
The 26-year-old lasted less than half-an-hour in his first appearance of the season for Leinster against Connacht after taking another blow to his lower back which has bothered him since
The Birtish and Irish Lions full-back had hoped to return in Saturday's PRO12 fixture at home to Cardiff Blues, but is now a major doubt for the back-to-back Heineken Cup fixtures against Clermont in December.
The defending European champions are also set to be without Isa Nacewa for four to six weeks after he suffered a broken hand during last weekend's win at the Scarlets.
Makeshift full-back Ian Madigan is expected to remain in the number 15 jersey against Cardiff.