World Rugby confirmed the match, due to be played at Paarl Gymnasium, has been moved to Danie Craven Stadium.
Following two tough Pool matches against England and Australia, Murphy has rotated his squad for the clash against Fiji, as Ireland – currently sitting level on points with England – chase qualification for the semi-finals.
Back row Diarmuid Mangan has been named captain for Tuesday, with Ireland’s starting XV showing 11 changes from Thursday’s bonus point win over Australia in Paarl.
Harry West comes in at fullback, with James Nicholson and Andrew Osborne continuing on the wings. Sam Berman, who linked up with the squad in South Africa this week, starts in the Ireland midfield alongside John Devine for his first cap at U20s level.
There is a new half-back pairing as Matthew Lynch starts alongside Oscar Cawley.
In the pack, George Hadden, Danny Shehan and Fiachna Barrett are named in the front row, with Evan O’Connell and Joe Hopes in the second row. Mangan captains Ireland from blindside flanker, with Dan Barron set for his Ireland U20s debut at openside and Brian Gleeson continuing at number eight.
Murphy has strong options on the bench with Max Clein, George Morris, Ronan Foxe, Charlie Irvine and Gus McCarthy providing the forward reinforcements, and Jack Oliver, Sam Prendergast and Henry McErlean competing the 23.
Commenting ahead of the game, Murphy said: “It has been a demanding couple of weeks with short turnarounds between our Pool matches, so it is important for us to use our squad wisely and we have selected the best 23 players for Tuesday’s challenge against Fiji.
“There is real excitement among the group as players get their starting opportunity in a green jersey and we’re looking forward to seeing how they perform and put their best foot forward for the team as we bid to finish the Pool stages strongly and give ourselves the best chance of progressing through to the semi-finals.”
Tuesday’s match is live on Virgin Media Two in Republic of Ireland and on World Rugby platforms where there is no local broadcaster.
16. Max Clein (Garryowen/Munster)17. George Morris (Lansdowne/Leinster) 18. Ronan Foxe (Old Belvedere/Leinster) 19. Charlie Irvine (Queen’s University/Ulster) 20. Gus McCarthy (UCD/Leinster) 21. Jack Oliver (Garryowen/Munster) 22. Sam Prendergast (Lansdowne/Leinster) 23. Henry McErlean (Terenure/Leinster).