Once was enough for Ireland.
The last time the Irish were in Rome, to finish the 2013 Six Nations, they lost to Italy for the first time in the tournament.
They won't be underestimating the Italians again on Saturday.
"They are at their best ... at home," lock Devin Toner says. "So we're under no illusions that it will be a lot tougher than people think.
"They've got a vast amount of experience, and they're very, very passionate at home, so we've got a very tough game ahead of us. We'll let everyone else think about points difference and all that. Literally, our sole focus is getting the win in Rome."
The form-book backs Ireland to win, and kickstart a campaign to accomplish successive championships for the first time in 66 years.
Loosehead prop Jack McGrath says they can deal a psychological blow by getting on top in the scrums, in which the Italians take great pride. He will mark tighthead Martin Castrogiovanni, who has 95 more caps than McGrath's dozen.
"They really want to shove their scrum in your face," McGrath says. "Their lineout maul too, that's their bread and butter and where they pride themselves the most. If we can meet them in that area and maybe go one better, that's what we ideally want to do. But it's not just doing it once; it's doing it every time.
"So it's up to us as a pack to really get stuck into them early, and turn it around on them. They are unbelievably passionate people so it will be really tough."
Ireland has gambled on picking flanker Sean O'Brien, who returned from a five-month injury only last week, although he appeared to have never been gone. O'Brien was in because No. 8 Jamie Heaslip was too late recovering from a shoulder injury.
Flyhalf Ian Keatley will start in his first Six Nations, alongside Jared Payne and Robbie Henshaw, the first Ireland midfielders to mark their tournament debut together since 2000, when Brian O'Driscoll and Mike Mullins ran out against England.
Italy has won only one of its last 12 tests. That makes the chance very slim of coach Jacques Brunel fulfilling his stated ambition of turning Italy into a title contender within three years of his appointment. He took charge at the end of 2011.
Confidence was high after winning two matches in 2013, then evaporated as Italy failed to win a match last year for the first time in five years. Avoiding embarrassment is the main goal this time.
"There's a different spirit now," Italy scrumhalf Edoardo Gori says. "We are a lot more calm. There's not that tension that maybe we put on ourselves after two victories in the 2013 Six Nations."
Brunel says starting with Ireland, the defending champ and favorite, is tough, "but will give us a bit of an impression of our ambitions this year."
"We beat them two years ago, and we hope to have that spirit in the first game. And we hope that Ireland won't be at a high level right from the start of the tournament."
In the only changes from the 22-6 loss to South Africa in November, Benetton Treviso flanker Francesco Minto and Zebre's Scottish-born lock George Biagi have replaced the injured Samuela Vunisa and Quentin Geldenhuys.
Italy: Andrea Masi, Leonardo Sarto, Michele Campagnaro, Luca Morisi, Luke McLean, Kelly Haimona, Edoardo Gori; Sergio Parisse (captain), Francesco Minto, Alessandro Zanni, Joshua Furno, George Biagi, Martin Castrogiovanni, Leonardo Ghiraldini, Matias Aguero. Reserves: Andrea Manici, Alberto De Marchi, Dario Chistolini, Marco Fuser, Matteo Barbini, Guglielmo Palazzani, Tommaso Allan, Giambattista Venditti.
Ireland: Rob Kearney, Tommy Bowe, Jared Payne, Robbie Henshaw, Simon Zebo, Ian Keatley, Conor Murray; Jordi Murphy, Sean O'Brien, Peter O'Mahony, Paul O'Connell (captain), Devin Toner, Mike Ross, Rory Best, Jack McGrath. Reserves: Sean Cronin, James Cronin, Martin Moore, Iain Henderson, Tommy O'Donnell, Isaac Boss, Ian Madigan, Felix Jones.