Ireland suffered defeats to France, England and tournament hosts Argentina, while Samoa lost out to Wales, defending champions New Zealand and Fiji.
Irish Coach Allen Clarke has made nine changes in personnel, some enforced, for this must win clash.
Tournament ending injury to Darren Hudson sees Andrew Boyle, a recent call-up to the squad, make his first start of the tournament on the right wing. Munster's Mike Kelliher replaces Hudson in the extended squad while fellow Munster man Simon Zebo maintains his left wing position.
A new centre paring sees Brendan Macken and David McSharry start with Michael Heaney in the scrum half position and Noel Reid partnering him at half back.
Four Munster players will feature in the forwards with Paddy Butler maintaining the No 8 jersey and Bryan Cagney starting in the front row. Brian Hayes and Brian O'Hara have a chance to impress in the second row and back row respectively with David O'Callaghan and Dominic Ryan making way to the bench.
Macken, Reid, Heaney, Hayes and O'Hara all saw action as replacements in Ireland's last game in Pool B, a 24-21 loss to Argentina in Rosario.
Ireland and Samoa met in a 7th-8th place play-off at last year's IRB Junior World Championship in Japan, with the young Samoans claiming a tight 9-3 win.
Current squad members O'Callaghan, Ryan, Hayes, O'Connell and Rhys Ruddock, who is Down Under with the senior squad, played against the Samoans twelve months ago.
15 - Andrew Conway (Blackrock College/Leinster)
14 - Andrew Boyle (UCD/Leinster)
13 - Brendan Macken (Blackrock College/Leinster)
12 - David McSharry (UCD/Leinster)
11 - Simon Zebo (Cork Constitution/Munster)
10 - Noel Reid (UCD/Leinster)
9 - Michael Heaney (Belfast Harlequins/Ulster)
1 - Bryan Cagney (UCC/Munster)
2 - Niall Annett (Belfast Harlequins/Ulster) (capt)
3 - Martin Moore (Lansdowne/Leinster)
4 - Brian Hayes (Cork Constitution/Munster)
5 - Ben Marshall (UCD/Leinster)
6 - Jordi Murphy (Blackrock College/Leinster)
7 - Brian O'Hara (UL Bohemians/Munster)
8 - Paddy Butler (Shannon/Munster)
16 - David Doyle (UCD/Leinster)
17 - Denis Buckley (Corinthians/Connacht)
18 - David O'Callaghan (UCC/Munster)
19 - Dominic Ryan (Lansdowne/Leinster)
20 - John Cooney (UCD/Leinster)
21 - James McKinney (Queen's University/Ulster)
22 - Eoin Griffin (Corinthians/Connacht)
IRELAND'S IRB JUNIOR WORLD CHAMPIONSHIP RESULTS
Saturday, June 5: Ireland 22 France 25, Estadio El Coloso del Parque, Rosario
Wednesday, June 9: Ireland 21 England 36, Estadio El Coloso del Parque, Rosario
Sunday, June 13: Argentina 24 Ireland 21, Estadio El Coloso del Parque, Rosario