Wales lock Alun Wyn Jones will be out for a fortnight with knee ligament damage suffered against Ireland on Saturday.
The Ospreys second row captained the Welsh to victory in Dublin, but suffered the injury in the second half of the game after a nasty collision.
He stayed on initially before leaving the field in the last ten minutes, and Warren Gatland revealed that he has medial ligament damage when he announced Wales' World Cup squad.
As a result, Wales have selected five second rows in their squad, but Gatland is optimistic that Jones will be ready to go for the start of the tournament.
"Alun Wyn should only be out for a couple of weeks but you never know with medial [ligament] stuff," said Gatland.