He said that lock Donncha O'Callaghan had suffered a knee injury setback on Wednesday. The injury, which he sustained playing for Munster recently, prevented O'Callaghan from taking a full part in Monday's squad session but he was able to train at the RDS on Tuesday.
The Corkman's left knee was tested yesterday and a call was made this morning that he will not be fit to play in Ireland's RBS 6 Nations opener on Saturday.
O'Callaghan's injury sees Leo Cullen promoted from the replacements bench. He will line out in the second row alongside Paul O'Connell, as he did against Fiji in November.
Munster's Donnacha Ryan has taken Cullen's place on the bench and is in line for his first RBS 6 Nations cap.
Saturday's game will mark Cullen's first Six Nations game since he started against Wales in March 2003, but McNaughton has no fears about the big Newtownmountkennedy man stepping up to the plate.
"Leo is an experienced player, a Heineken cup winner and captain with Leinster. He was in squad in November and he's a very experienced guy to bring into the team," explained the Irish manager.
IRELAND Team & Replacements (v Italy, 2010 RBS 6 Nations Championship, Croke Park, Saturday, February 6, kick-off 2.30pm):
15 - Rob Kearney (UCD/Leinster)
14 - Tommy Bowe (Ospreys)
13 - Brian O'Driscoll (UCD/Leinster) (capt)
12 - Gordon D'Arcy (Lansdowne/Leinster)
11 - Andrew Trimble (Ballymena/Ulster)
10 - Ronan O'Gara (Cork Constitution/Munster)
9 - Tomas O'Leary (Dolphin/Munster)
1 - Cian Healy (Clontarf/Leinster)
3 - John Hayes (Bruff/Munster)
4 - Leo Cullen (Blackrock College/Leinster)
5 - Paul O'Connell (Young Munster/Munster)
6 - Kevin McLaughlin (St. Mary's College/Leinster)
7 - David Wallace (Garryowen/Munster)
8 - Jamie Heaslip (Naas/Leinster)
16 - Rory Best (Banbridge/Ulster)
17 - Tom Court (Malone/Ulster)
18 - Donnacha Ryan (Shannon/Munster)
19 - Sean O'Brien (Clontarf/Leinster)
20 - Eoin Reddan (Lansdowne/Leinster)
21 - Paddy Wallace (Ballymena/Ulster)
22 - Keith Earls (Young Munster/Munster)