Joe Schmidt admitted Garry Ringrose's selection for Saturday's huge NatWest 6 Nations showdown with Scotland is a "needs must" scenario, but backed the 23-year-old Leinster centre to shake off any rust and prove his class.

Ringrose had ankle surgery in early January and only returned to action a fortnight ago for his province in the Pro14 hammering of Southern Kings.

Championship-ending injuries to Robbie Henshaw (shoulder) and then Chris Farrell (cruciate) have unexpectedly opened the door for Ringrose to play a key role in Ireland's Grand Slam ambitions.
And Schmidt has absolute confidence he will not be off the pace in the Aviva Stadium pressure-cooker.

"There are always concerns about players for different reasons," he said.

"I think Garry's only had six games in this entire season so that's something that you calculate in. At the same time, sometimes you don't have the luxury of a plethora of options.

"Garry Ringrose has been extraordinary when he has played for us. He's done an incredible job. The last time he did play for us, against Japan (last June in a 50-22 summer tour win), he was absolutely outstanding in the back line along with Keith Earls.

"We're hoping he can hit the ground running and get straight back into that form. He's a smart player. 

"It's a needs-must situation but it's a situation where we've got a lot of trust and faith in Garry."

In the only other change to the starting 15 that lined up against Wales, Tadgh Furlong returns to the front row having recovered from a hamstring injury.

Andrew Porter drops to the bench but Devin Toner has done enough to hold off the challenge of Iain Henderson, also fully fit again after a hamstring problem.

"It was just a case of trying to keep some continuity" Schmidt said of Toner's second-row partnership with James Ryan. 

"Iain possibly could have played against Wales but it would have been a risk. It's just a case of trying to keep a balance. It also potentially adds a bit to our last 20 minutes, 30 minutes of the game where an athlete like Iain can come on."

Meanwhile Sean O'Brien returns from his hip injury to captain Leinster tomorrow night in their Pro 14 clash with the Scarlets.

Schmidt said he'll be monitoring the back-row, who could now come into the reckoning for the St Patrick's Day showdown against England.

"I'll be watching how he leads the side because he tends to lead himself pretty well once he's on the pitch. That's of interest to us without a doubt."

Follow Ireland v Scotland on Saturday (KO 2.15pm) via the live blog on RTÉ.ie/Sport and the News Now App, or listen live on RTÉ Radio 1, with commentary from Michael Corcoran and Donal Lenihan.