D'Arcy was hurt while tackling Italy fly-half Andrea Masi in the 26th minute of the tournament opener at Croke Park.

Ireland coach Eddie O'Sullivan said: "Gordon suffered a stress fracture of his forearm. That's the end of his 6 Nations and he will have an operation on Monday."

D'Arcy's injury capped a far from enjoyable afternoon for Ireland, who produced an unconvincing opening to their RBS 6 Nations campaign.

Girvan Dempsey crossed in the 18th minute in an encouraging start and with Ronan O'Gara kicking the goals, they remained in the driving seat.

But Italy's perseverance paid off when skipper Sergio Parisse completed a line-out catch and drive that was approved by the television match official.

Full-back David Bortolussi added a penalty to blow the match wide open but Ireland held out and O'Sullivan admitted his side had won "ugly".

O'Sullivan said: "In the context of the 6 Nations I'm happy with that performance because it's the first game of the championship.

"You want to hit the ground running but historically you don't. After the initial shadow boxing of the first 10 or 15 minutes we played some good rugby.

"We created opportunities but unfortunately didn't finish them. We lacked a bit of accuracy and had we taken a couple of those chances it would have made our job easier.

"Italy managed to slow down our ruck ball which killed off our attack. It was a performance that turned ugly as it often has in the past against Italy and we had to dig out an ugly win.

"It wasn't the display I wanted because it wasn't polished but it's the first day of the championship and it can happen that way."