The one backline change sees replacement against the Scots, Shane Gahan, preferred in the centre with Ian McKinley trading places with Gahan on this occasion.
Explaining the changes, Ireland coach Allen Clarke said, "With Adam Macklin and Shane Gahan coming into the starting lineup, we have focused on improving the accuracy and usage of ball from our set piece. The response from the players after a below par performance against Scotland has been excellent and there is a strong determination to finish the Six Nations with a quality performance."
Despite losing to Scotland last Friday night, earlier championship wins over France and England and an away victory in Italy leave the U20s in pole position to end the championship in top spot
Meanwhile, Wales have named Ospreys academy and Aberavon flanker Justin Tipuric as their captain for this game and will also be looking to build on their 34-14 win over Italy with a second win of the Championship.
Tipuric was a member of Wales' Under 20 squad that reached the semi-finals of last season's Junior World Championship and former Scarlets head coach Phil Davies, now Wales Under 20 head coach is hoping his experience will help his young side against Ireland.
He said, "The boys produced a pleasing performance on Friday night in the win over Italy - the Italians had run all the other nations close and we showed a step-up in intensity and a clear improvement on our earlier matches.
"Ireland pose a different challenge. They have some good ball winners and a very good kicking game, and they've only lost one game so far, to Scotland last weekend. However, if we can build on last weekend, do the basics well with a positive attitude, and express ourselves, our performance will follow the attitude I'm sure."
Tickets for Friday night's game at Llanelli are £5 for children and £7 and £10 for adults and can be purchased on matchday from the Parc y Scarlets ticket office, by calling +44 1554 783 900 or via http://www.ticketmaster.co.uk/
Ireland U20: David Kearney (Lansdowne/Leinster); Ronan O'Mahony (Garryowen/Munster), Shane Gahan (Lansdowne/Leinster), Eamonn Sheridan (Lansdowne/Leinster), Michael Keating (Clontarf/Leinster); Ian Madigan (Blackrock College/Leinster),Matthew Healy (Lansdowne/Leinster); Jack McGrath (St. Mary's College/Leinster), Thomas Sexton (Old Belvedere/Leinster), Adam Macklin (Belfast Harlequins/Ulster); Ciaran Ruddock (Neath/Exiles), James Sandford (Queens University/Ulster); Rhys Ruddock (Millfield School/Exiles), Dominic Ryan (Lansdowne/Leinster), Peter O'Mahony capt (Cork Constitution/Munster) . Replacements: David McGregor (Ballynahinch/Ulster), Paddy McAllister (Ballynahinch/Ulster), Mark Flanagan (UCD/Leinster), Michael Noone (Seapoint/Leinster), Conor Murray (Garryowen/Munster), Andrew Burke (Garryowen/Munster), Ian McKinley (UCD/Leinster).