Wing Keith Earls and centre Luke Marshall departed with a shoulder injury and concussion in quick succession, and were soon joined on the sidelines by Luke Fitzgerald after the substitute wing incurred a knee problem.

Uncapped scrum-half Paul Marshall was left as the only available three-quarter replacement, so coach Declan Kidney opted to shift O’Mahony to the left wing.

“It was a mad one all right, I certainly never saw myself playing 50 minutes on the wing for Ireland in a Six Nations game,” the Munster back row said.

“But these things happen and at least we’ve blooded a lot of players in this Six Nations. It’s been a huge learning curve.”

Further hindering their chances of avoiding a first Six Nations loss to Italy was the sin-binning of Brian O’Driscoll, Donnacha Ryan and Conor Murray as Ireland imploded on multiple fronts.

Along with Rob Kearney and Craig Gilroy, fly-half Paddy Jackson was a back who managed to complete the 80 minutes amid rapidly shifting sands at the Stadio Olimpico.

“The amount of guys we lost didn’t help and Italy are a very strong team. The number of penalties we gave away killed us,” Jackson said.

“Those injuries were something I’ve never experienced before. I looked around and both Lukes were gone, Brian was in the bin and Pete O’Mahony was on the wing.

“I wanted to clam things down by kicking for territory but our kick-chase wasn’t so strong.

“It was about striking a happy medium between keeping the ball and securing territory, but those penalties killed us.”

It was a chastening afternoon for Ireland and arguably their lowest point of the championship since Italy joined in 2000.

The line-out was a disaster, their defence uncharacteristically fragile, indiscipline was rife and they were comprehensively outmuscled by the Italian pack.

Yet for all their shortcomings, they remained in touch on the scoreboard through the superb place kicking of Jackson, who landed five from six penalty attempts, three of them arriving while Sergio Parisse was in the sin-bin.

But Italy, roared on by a noisy capacity crowd at the Stadio Olimpico and inspired by Parisse and retiring prop Andrea Lo Cicero, were irrepressible and were more comfortable winners than the scoreline suggests.

“It’s not great to be part of the first team to lose to Italy, so we’re very disappointed. But Italy played well,” Jackson said.

“The young guys are chuffed to have got our chances, but we haven’t got a win yet.

“This has been the biggest learning period I’ve had in my career so far. The last three weeks have been up and down.”