The best number 8 in the world, many contend, starts today's game out of position.

Caelan Doris, the 24-year-old Leinster back row, has been shifted to the flank for Ireland's Six Nations clash with Italy in Rome.

Head coach Andy Farrell has promoted Jack Conan, the starting number 8 for all three Lions Tests two years ago, from the bench and the thinking is that Doris is more flexible and better able to fulfil duties at 6.

Everyone can see Farrell’s reasoning for this Guinness Six Nations round three clash but the fact remains that Doris’s outstanding performances in the opening wins over Wales and France only franked the claim that he’s top of the world at the back of the scrum.

"If you were picking who was the best number 8 in the world, he wouldn’t be too far off it at the moment," Leinster senior coach Stuart Lancaster told RTÉ Sport in the wake of Doris’ player of the match performance against France two weeks ago.

The Mayo native, who moved to Dublin to attend Blackrock College aged 12 and joined the Leinster academy in 2017, made 117 metres from 18 carries, second only to Hugo Keenan on the day.

He appeared to be everywhere as he completed the full 80-minute shift for the second week in a row.

Doris was just nudged out for the man of the match nod against Wales by the outstanding Keenan; he scored the opening try and put in 18 tackles in another typical all-action outing.

Amidst the stats there’s the things that can’t be counted: the footwork before contact, the ball-handling skill, the ability to offload after the first hit, as exemplified by his assist for Garry Ringrose’s try against France.

It had vision, control and execution and as he won the contact and worked his body into the correct position to pass/offload for his Leinster team-mate.

"Doris could play at inside centre because he’s got footwork so good he’s going to get beyond you and get the offload away," former England out-half Stuart Barnes said on The Ruck podcast. "His running lines, his vision, he’s fantastic.

"He’s right up there now with [New Zealand’s Ardie] Savea as the best number 8 in the world in current form, and he’s been there all season."

Doris’ performances over the last three weeks only serve as a refresher of what he is capable of.

Ireland’s 2021 home win over New Zealand was secured by Doris’ second-half try and accompanied by another man of the match medal, and subsequently the Autumn Nations Player of the series award. He stood out in the historic series win in New Zealand last summer.

It might all appear to be a natural progression but a series of injuries, only two years ago, put big question marks over the former Blackrock College captain’s rugby future.

Leinster and Ireland are always extra cautious when it comes to head injuries but, as many players forced into early retirement can testify, there are no guarantees.

His Champions Cup and Six Nations debuts, in 2019 and 2020, were both cut short by early head knocks as the sight of the young man leaving the field with medics became worryingly common.

Doris, who made his club debut in 2018 and has since scored 10 tries in 64 appearances in blue, was withdrawn from the national squad prior to the 2021 Six Nations with "some symptoms that could be associated with concussion".

He subsequently spoke openly about the issues, detailing short-term memory loss and speech issues. The Ballina man visited a specialist in Birmingham and was stood down for four months.

"I’ve gotten peace of mind from taking that break, being comprehensively checked out and I’ve got a few things in place as well, around trying to manage it," said Doris, who today wins his 26th cap.

"Neck strength, tackle tech, the scrum cap, even a gumshield that measures g-force, so there is a fair bit I’m doing."

Doris take a lineout catch against France

Doris stands 6' 3" and weighs in at 16st 8lbs, noticeably building up his physique over the last two years.

"He's come on massively," adds Lancaster.

"Obviously he went through a period of not playing so much because he was off.

"That period for him, he grew, not just physically, but he grew mentally as well in terms of his maturity. He’s always been very mature, he has an inner confidence and an inner self belief but that has shown itself more and more.

"His leadership voice is starting to be heard within meetings and that confidence now that he has in his physical and technical ability is showing, as you can see."

No disrespect to Italy's back row today but Ireland and Doris will face tougher tasks than this in the near and mid-term and then Farrell will have to choose between accommodating others and putting his best loose-forward where he plays best.

"They [Doris and Keenan] were academy lads when I came in, in 2016," states Lancaster, who has witnessed first hand the Connacht man's progression.

"To coach them now for seven years and to see them go from 17, 18, 19-year-olds to be fully fledged internationals. If there was a British and Irish Lions team at the moment they'd all be in it."

There may well be more to come from Doris but in a frank assessment, Lancaster can't hide the fact that, on current form, it's hard to know where he can get better.

"You'd like to say there is more to come from him but he has set a very high bar at 24, a very high bar."

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Watch live coverage of Italy v Ireland (2.15pm) on RTÉ2 and RTÉ Player, follow our live blog on RTÉ.ie/Sport and the RTÉ News app, or listen to live commentary on RTÉ Radio 1.

Watch live coverage of France v Scotland (Sunday, 3pm) on RTÉ2 and RTÉ Player.