Reddan, the former Wasps, Munster and Connacht No.9, has received the nod from Declan Kidney to replace Conor Murray after the Munster scrum-half was ruled out with a knee injury.
The 22-year-old will miss the rest of the tournament after suffering bruising to the joint in 17-17 draw with France, while captain Paul O’Connell also misses out against Scotland with a knee injury.
Hooker Rory Best will lead the side out in Dublin and front-row partner Ross insists Ireland are strong enough to cope without O’Connell and Murray.
“It was good to hear Connor’s injury’s not so bad and in Eoin Reddan we’ve a ready-made replacement,” he said.
“He plays with Jonny Sexton at Leinster so there’s already that stability there.
“Paul’s obviously a big loss but there are good players looking to come in and take their own opportunity.
“The boys were gutted in the dressing room after the game [against France], it felt like a loss. It was disappointing that we gave away that penalty [to tie the game] having built up good pressure on defence.
“Our own mistakes put us in that position. We weren’t as accurate at set-piece as we needed to be – at this level there is no margin for error and little timing issues can cost you. We’ll work on them this week.”
Ireland built an 11-point lead going into half-time against an unbeaten French team before a rising error count and inconsistency at the lineout allowed Thierry Dusatoir’s team back into the game.
And Ross admits Ireland must improve their discipline to keep their championship hopes alive with victory against Scotland.
“For us obviously now it’s more about performance,” he added.
“The Scots will look to play a quick tempo, wear you out by taking you through the phases, and then try and catch you out with some of their quick backs.
“They’re strong at line-out and bring good size with [Richie] Gray and [Jim] Hamilton. They’ll play a lot of phases and look to wear you out- it’ll have to be a very disciplined performance from us on defence.”
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