27-year-old Ongaro has all-but-shaken off a groin injury sustained in the Azzurri's final warm-up match last weekend against a Super 10 selection in Sicily, and looks set to earn his 27th cap, ahead of flu-victim Giorgio Intoppa.
"I have good news about Fabio Ongaro,'' explained Kirwan today. ''He is 95% likely to start the match as hooker - which is great news.
"We have done good work in training this week - I have seen a determination and I'm sure on Saturday after a relaxing night tonight, anyone who has not been able to give their best will be able to.
"Our target is to win on Sunday and if that wasn't the case there would be no point in us being in the tournament," added the New Zealander, on the cusp of his third Six Nations campaign.
Taking his starting place is veteran Alessandro Troncon, who is readying himself for his first Six Nations start for two years.
"The joy to play a match in one of the most important rugby tournaments in the world in unbelievable," said the 31-year-old club mate of Ongaro.
"I'm ready to give my best to this young team, and if we will play like we can do I'm sure we can offer to the Flaminio fans a great match.
"The Irish are strong and very good overall - but here in Italy they have never had it easy - and we have always played the first match at a high standard,'' added Troncon.