Dublin - Ireland reserve flyhalf Paddy Jackson will miss the Six Nations after dislocating his elbow, his province Ulster said on Tuesday, limiting the champions' options with Jonathan Sexton set to miss their opener in Italy.
Jackson requires surgery after suffering the injury in last weekend's European Cup defeat by Toulon and will be out for 10 to 12 weeks.
Ulster centre Stuart Olding is expected to be sidelined for a similar length of time because of an elbow operation.
Although Jackson had fallen behind Ian Madigan as understudy to British and Irish Lions flyhalf Sexton, the Leinster utility back has played mostly at inside centre this season, raising the possibility that both could have started on Feb. 7 against Italy.
Sexton has been advised to rest for 12 weeks after being concussed for the fourth time in a year in November's win over Australia. He should be available to play against France on Feb. 14.