Sexton was injured in the defeat to England last weekend and it has now been confirmed he suffered a grade two hamstring problem.

McCarthy is ruled out with a medial ligament injury in his right knee and joins Sexton and Simon Zebo, who broke a bone in his foot, on the sidelines.

Centre Brian O’Driscoll, full-back Rob Kearney, flanker Sean O’Brien and lock Donnacha Ryan also suffered knocks in the brutal encounter with England but all are hopeful of facing Scotland.

“Jonny’s scan revealed a grade two hamstring injury. Progress has been good so far, but it’s too early to say when he will return to play,” said team manager Mick Kearney.

“Mike has hurt the medial ligament of his right knee. It’s quite sore and he will be in a brace for two weeks. A further review will take place in two weeks.

“Brian had a recurrence of the soft tissue injury in his good ankle. Scans revealed no structural damage and he will do non-contact training today.

“Donnacha Ryan suffered a lower back muscle strain. Scans have excluded structural damage but he’s quite sore and won’t train this week. He’ll be reassessed at the weekend and at this stage he has a good chance of being available against Scotland.

“Sean O’Brien has recovered well from his stiff neck and tight hamstring and will train today. Rob is fine. He had a slight dead leg but trained fully.”