Accepting that the team failed to perform at the recent World Cup, the Munster lock views tomorrow's clash with Italy as an ideal chance to show what this Irish side is made of.
"The guys that are lucky enough to get the start against Italy are an awful lot of the guys that would have played in the games against France and Argentina," he told RTE's Drivetime Sport.
"For us it feels like a chance to redeem ourselves a bit. It was hugely disappointing, we know we all underperformed.
"When you train so hard for something and you come up short and you've no excuses, it's hard to find what went wrong. As players all we can do is play for the 80 minutes on the pitch and this is our chance to answer it."
Asked about whether the Irish camp has been quieter this week due to the World Cup disappointment and the pressure on the team and management, O'Callaghan admitted: "No, it hasn't. There's always fresh new faces, like Cian Healy and Luke (Fitzgerald), coming through.
"It's kinda like these guys are in the door and how much can we slag them and you know, trying to get stories on them.
"It has been really enjoyable, it always has been in the Irish camp. There's the perception that maybe some guys don't get on with each other, but that's not the case. Anyone around here would know that.
"You kinda live with each other for the next six weeks so you just have to get on."
Focusing on tomorrow's renewal of rivalries with the Azzurri, the Corkman knows Ireland will get nothing easy against Nick Mallett's side.
"We played Italy last year when we ended up getting a really good win in Rome. Everyone forgets that for the first 20 minutes or even the first half, there was only a score in it.
"It was really tough, the days of underestimating the Italians are gone. They should have probably beaten us in Belfast in the (World Cup) warm-up game and they'll be looking to avenge that."
WOOD BACKS FRANCE TO RETAIN TITLE: While former captain Keith Wood believes Ireland will bounce back in the 2008 Six Nations and redeem themselves after a World Cup to forget, the 36-year-old feels France have the strength in depth to retain the title they won so dramatically last year.
"Everyone knows Ireland had a disappointing World Cup, particularly looking at the calibre of players they have. But there is an opportunity for redemption now.
"First and foremost, the World Cup has to be put in the past. The lessons have been learned but, unless it's put out of their minds, they will never move on."
Wood, who feels he is too young to take on the Ireland team manager's post, added: "I'm fairly confident for Ireland but I think the French flair will prove too much.
"The French had gone a little bit stale under (Bernard) Laporte - he'd brought great discipline but perhaps got too obsessed by that. Now the players are itching to break free and I think they'll be awesome. As for who runs them closest, that's much of a muchness between England and Ireland."
Meanwhile, Munster back rower Denis Leamy, who has beaten off Jamie Heaslip for the Ireland number 8 jersey, is bracing himself for a bruising opener at Croke Park.
"Italy's main threat is in their front five and their back row. They've got big strong men who are quality rugby players. They've got good know-how about them. They've got a little bit more in common with South Africa than a lot of teams," said the Tipperary man.
Ireland are without the injured Paul O'Connell for the first few games of the championship, but Leamy has no doubts that Leinster veteran Malcolm O'Kelly can step up to the mark.
"Mal has been around for years, he knows the ins and outs of the game so well. If you're having anyone to replace Paul, you know Mal is ideal, he's ready made for it."
PARISSE HAS FAITH IN NEW NUMBER 10: New Italy captain Sergio Parisse has given Andrea Masi a vote of confidence ahead of tomorrow's Six Nations meeting with Ireland.
Masi, who is more known as a centre, has been handed his first Test start at out-half and he will partner Pietro Travagli in an untried half-back combination.
The 24-year-old Parisse said: "Masi has great qualities as a man and a player. I'm sure there won't be any problems because the squad will do their part and put him in the conditions to work at his absolute best without any risk of making a mistake."
Parisse will warn his troops not to fall into any mind games with Ireland tomorrow as the Stade Francais number 8 has been caught out before.
"The Irish are cunning and always try to make you lose your nerve. Last time, I myself had some problems with (Peter) Stringer. He was great in making me fall into traps.
"But now, and not just because I'm captain, I will not make any more mistakes. No one will be able to trip us up - we will be cool and think only about playing rugby," he added.
"I remember doing a couple of sessions with him years ago, and I have to say the change in his throwing is startling.
"He is not as good a thrower as Jerry Flannery, but he has developed a very competent throw. He has worked really hard, and he looks fitter than he was.
"What he does have over the majority of the Ireland forwards is the ability to take a ball at full speed, which means he is a viable addition, and a valuable one."
- Former Ireland hooker Keith Wood gives his opinion on Leinster number 2 Bernard Jackman, who has been named on the Irish replacements bench for tomorrow's encounter with Italy
"When I was coaching Ireland, Munster were playing particularly well but we tried to balance the numbers of players in the squad across the provinces.
"That wasn't the right thing to do. Munster were the best team in Ireland at the time and they should have been represented by the most number of players. That is what I am trying to do here.
"I have selected players on form, players with combinations and players playing on confidence. That is what this team is about."
- New Wales coach Warren Gatland, who coached Ireland between 1998 and 2001, explains the reasoning behind his decision to select 13 Ospreys players in his starting line-up for tomorrow's showdown with England at Twickenham
"Two weeks on, the way the Munster pack performed is very positive for me. Had it disintegrated it might have been fine for five minutes because I was playing for Wasps, before realising I was going to be playing behind most of the Munster guys for five weeks."
- Wasps scrum half Eoin Reddan, who will be back in the green of Ireland tomorrow, reflects back on his club's Heineken Cup pool defeat to Munster at Thomond Park
3 - The number of players in the Italian matchday 22 for Saturday's game that have scored tries in previous internationals against Ireland. Mirco Bergamasco (in 2006), Martin Castrogiovanni (in 2005) and Mauro Bergamasco (in 2001 and 2002) are their only try scorers included
25 - Ulster lock Carlo Del Fava will make his 25th appearance for Italy this weekend. The 26-year-old was born in Umtata, the capital of the former South African homeland of Transkei, his father is an Italian from Lucca and his mother is South African
30 - Leinster centre Brian O'Driscoll has led Ireland to 30 wins in his 42 games to date as team captain. He is Ireland's record try scorer (31) and also the country's record try scorer in the Six Nations with 17 touchdowns