Huge blow as Johnny Sexton and Peter O'Mahony are ruled out of Scotland clash
Johnny Sexton is out of Saturday's opening Six Nations game against Scotland after aggravating his calf injury when trying to run on Monday.
The out-half did not train at Carton House this morning and has been ruled out of the Murrayfield encounter.
Paddy Jackson will now start Saturday's game having led the backline against South Africa last summer and in the Australia clash last November.
Ian Keatley, who still has not been announced as part of the squad, and Rory Scannell are in a two-way battle to cover from the bench.
Peter O'Mahony is also out of the game after suffering a hamstring injury, while Andrew Trimble is a major doubt after suffering a groin injury.
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Forwards coach Simon Easterby confirmed the injury news but backed Jackson to thrive, while he added that he expects to see Sexton play in this year's Six Nations.
"Paddy has proven himself over a number of months, going back to the summer, that he can control the side and dictate the play. Johnny is one of the best 10s in the world, but we have to adapt," he said.
"That's the mark of this team, we can lose players in key positions and can adapt.
"With Johnny, it's purely now managing his return to training, that will take as long as it takes.
"He’s obviously had a number of lower limb injuries, one hamstring which we have managed along with Leinster through the Christmas period after the Autumn .
"We redressed the balance there in terms of the hamstring. He picked up a calf in the Castres game. He only managed 20 minutes in that game. He had to come off.
"As a result of that little calf strain he’s got, we don’t want to compromise his calf any further. We felt it best to leave him out this week and make sure that he is right for the upcoming games.
"It’s purely now that we manage his return to full training. That will take as long as it takes. We’ve no time scale on that. He just felt tightness yesterday and we felt it was in the best interest of Johnny that he didn’t try and push into today and further into the week.
"There's no timescale, felt tightness yesterday and felt it was in Johnny's best interests not to push it.
"It's a case of monitoring or managing it.
"We've got Keats in with Paddy Jackson and Rory Scannell who has been slotting in at No 10, we feel we have enough cover in that position to make selections for this weekend.
"Whatever happens this weekend we'll make further assessments."
Asked if bringing Ian Madigan into the fold was a possibility, Easterby added: “Unfortunately he couldn’t be with us last week anyway because he was on the bench for Bordeaux against Clermont so it compromises his position with us when he is not playing in Ireland and we are trying to support those guys who are staying here.
"Circumstances may allow us to look outside of that but as it happens at the moment we have got those three guys in and Mads hasn’t been selected in the squad. He couldn’t be included last week so that hasn’t really helped his cause.”
On the likelihood of Trimble being available, he said: “He ran today and was reasonably effective. It needs to be high intensity but it is a case of having to monitor him and make sure that he is fully fit and not risking a player if he is not fully right.”