Cape Town - Ireland will be without flyhalf Johnny Sexton for this weekend's Six Nations opener against Scotland at Murrayfield.
Sexton was set to take a full part in training on Tuesday but the decision has now been made to stand him down for Saturday's contest.
Paddy Jackson is now likely to start at Murrayfield, as he did for Ireland when Sexton missed last year's tour to South Africa.
Munster flyhalf Ian Keatley linked up with the squad as cover earlier this week, while Rory Scannell, Munster's uncapped back, can also cover flyhalf and is in the squad.
Sexton has been battling with a calf injury and according to a tweet from the IRFU: "Johnny did light running but still feeling some tightness. He will continue to rehab but won't be selected this weekend."
Ireland flanker Peter O'Mahony has also been ruled out with a hamstring issue and is set for a scan, while wing Andrew Trimble is being monitored.