Ireland required a late drop-goal from Ronan O'Gara to avoid a first defeat by Italy in the RBS 6 Nations.
The Azzurri crept 11-10 ahead in the 76th minute through a try from Luke McLean, and one of the championship's greatest upsets looked likely.
But Ireland, who started as overwhelming 1/8 favourites, hit back two minutes later when O'Gara was on target from in front of the posts to clinch a 13-11 success.
It was a dismal start to the campaign for a side hoping to be in the title mix, but there was nothing on show at the Stadio Flaminio to suggest they can win the Six Nations.
Brian O'Driscoll crossed in the 44th minute while Jonathan Sexton kicked five points, but it was otherwise a torrid afternoon for the 2009 champions.
They dazzled with some thrilling running but time and again failed to capitalise, making desperately hard work of subduing stubborn but limited opposition.
Worryingly for Ireland, they are group rivals at this year's World Cup and the teams are due to meet on October 2. Italy will only have been encouraged by Saturday's events.
The lack of composure at crucial moments will concern head coach Declan Kidney, with chances blown by handling errors from O'Driscoll, Gordon D'Arcy and Keith Earls.
Ireland were missing 12 Test players to injury, among them Jamie Heaslip and Tommy Bowe, yet still fielded a side averaging 35 caps per player.
Mirco Bergamasco kicked two penalties for the hosts before McLean touched down.