Ireland captain Johnny Sexton joked that a cheekbone problem was the best facial injury to suffer as he declared himself fit for his team's Six Nations opener against Wales on 4 February.

Sexton hasn't played since and has been training in a protective face mask.

"[The surgeon and the doctor] said it's probably the best injury to have on your face," laughed the 37-year-old.

"If you could pick one bone, pick that one.

"I was training last week, just had a funny face mask on. Keep that on this week in training and it comes off next week, so good to go next week."

Sexton remains undisputed first-choice 10

Sexton missed Leinster's last three games, including Heineken Champions Cup victories over Gloucester and former club Racing 92.

The Dubliner will be 38 by the time of this year's World Cup in France but remains Ireland's undisputed first-choice number 10 going into the championship.

Ross Byrne and Jack Crowley have been selected in reserve, with Joey Carbery a shock omission from Andy Farrell's 37-man squad.

Farrell said all of his fly-halves have room for improvement, as he explained Carbery's absence.

"I understand it because it's not as though he's been playing poorly, his form has been pretty good," he said of the surprise which greeted his decision to drop the Munster man.

"But there's been a bit of feedback, like we do with a lot of players who didn't make the squad, and Joey understands that.

"Ross Byrne has been getting feedback for the last couple of years and couldn't get in the room.

"He's improved on things we've been asking of him, so he gets the chance to see whether he can convert to the international stage, he's earned the right to be able to do that.

"And 100 per cent Joey will be working away hard to get back in.

"It's a great place for us to be. A little bit of depth, a little bit of competition, people fighting to be part of this Irish squad."