Who will replace Paul O'Connell as Ireland captain?
Joe Schmidt's decision on the next Ireland captain will be made in the coming weeks, so who should replace the Limerick legend?
It is the biggest vacancy in Irish rugby this winter, a job that has been filled by the two finest professionals the game has produced over the course of the past 12 years and the choice is Joe Schmidt's to make.
Captaincy is an honour and a responsibility and the decision the New Zealander makes at the beginning of this World Cup cycle will have a large bearing on the future of his team, setting the tone for the years ahead.
Japan in 2019 seems a long way away, but the age profile of the squad in England means there is set to be a large turnover of players in the next four years. Schmidt is not committed to seeing that period through, but over the next two years he will begin the process of building towards that tournament. His first big decision is to find a replacement for Paul O'Connell who has retired from international rugby.
Last time he named a captain, the coach did it in the week of his first Test in charge against Samoa, but this time he will have to move earlier than that given the obligations for the incumbent include attending the Six Nations launch on January 27.
He began the process last night by asking his squad members to suggest options, but the decision will ultimately be his. Five of his World Cup squad have captained Ireland at one time or another in Brian O'Driscoll or O'Connell's almost unbroken service in leadership of the national team.
Jamie Heaslip was handed the responsibility by Declan Kidney, but O'Connell wasn't available and when Schmidt came into the job he relegated the Leinster No 8 to the role of vice-captain.
Before the Kiwi took over, Peter O'Mahony led the tour of the United States and Canada, while Rory Best, Eoin Reddan and Sean O'Brien have all skippered the side at various points in recent years.
In total, however, for 111 of the last 155 Test matches Ireland have been led by either O'Driscoll or O'Connell. When Schmidt looks around his dressing-room, he will see leaders a plenty but his captain must set the tone for the identity he wants his team to have over the next four years.
Some will say he should go all in for the future, ditch the old guard and press on for World Cup success but that is not a realistic option given he is judged on Six Nations success by the IRFU.
Union performance director David Nucifora has set the tone by stating his aims for 2016, saying: "The primary thing, in the eyes of the players and coaching staff, is to defend our Six Nations title. That's the thing that's directly in front of us, that's the starting point for us, to go out and defend that."
The first move towards that is selecting a leader to take the team forward. So, who is in the frame?
The incumbent, Heaslip has led Ireland out on 12 occasions and took over the captaincy from O'Connell when he went down at the World Cup.
At 31, he will probably feel that he has done his time and deserves the job on a full-time basis yet doubts remain about his leadership credentials.
Undoubtedly, the Naas native is a brilliant rugby player who leads by deed on the pitch and sets the tone for his professionalism off it. He is rarely injured, almost always performs and is comfortable at the highest level. A five-times-capped Test Lion, he has earned the trust of a host of coaches.
It is away from the pitch when the No 8 lets himself down, however, and, while it might not be the primary focus of the role, the additional engagements required of a skipper are pivotal to setting the tone for the team and show the public face of the squad.
When the mood takes him, Heaslip can be engaging company, a funny and thoughtful interviewee who thinks outside the standard selection of stock answers.
However, too often his too-cool-for-school approach lets him down in front of the cameras. He can come across as arrogant and churlish when the mood takes him.
Heaslip will remain an important and valued part of the Ireland set-up, but Schmidt may look elsewhere. The role just doesn't suit him.
At every level of the game, O'Mahony has been named captain of the team he is playing for and he appears the natural long-term successor to his old provincial colleague.
His age profile is on the money, even if it is undermined by a long list of injuries and concerns about his longevity as Ireland's warrior-in-chief who puts his body on the line repeatedly during games.
Schmidt hadn't taken over when the then 23-year-old led his country to North America during the 2013 Lions tour, but he was set to take over and travelled with the squad so it is likely that he had a role in his elevation.
When fit, O'Mahony has been one of the first names on Schmidt's team-sheet since he took over and he was one of his country's top-performers at the World Cup before he ruptured his cruciate ligament against France.
He has captained Munster since he was 23 and while he cuts a no-b******t figure off the park, he takes his off-field obligations seriously and with gravitas even if he could do with lightening up just a touch.
It is clear that he commands the respect of all of his peers and is a popular figure in the dressing-room who sets the tone with his abrasive physicality on the pitch.
Unfortunately, he won't be available for the Six Nations and is a doubt for the three-Test tour of South Africa in June. He might be the long-term choice looking towards 2019, but Schmidt needs an immediate option.
At 33, the Ulster captain's ability to go another full World Cup cycle is in doubt yet, in the short-term, he seems the perfect choice to take over the role.
Ireland's most-capped hooker has rarely, if ever, let his country down and was one of his side's best performers at the recent World Cup.
The softly-spoken Armagh man is universally liked and respected and despite his age remains an automatic first-choice player going into the Six Nations; particularly as the injuries mount for Schmidt and his team.
Politically, he could be the preferred choice for the union given Leinster and Munstermen have, by and large, skippered the team since Paddy Johns and Dion O'Cuinneagain's time in the late 1990s. How much of a factor that is for Schmidt, however, is hard to discern.
What is clear is that Best would be a popular selection, at least in the interim as O'Mahony recovers from injury. He is not the divisive figure of Heaslip and has bags of leadership experience as one of the squad's vice captains and the skipper of his province.
Whether the additional responsibility would distract from his primary roles as hooker is a concern, yet Best already takes on more than his fair share of media and commercial responsibilities and it doesn't appear to affect his performance.
Seems the smart choice.
Ireland's best player at the World Cup, O'Brien is a natural-born leader who sets the tone with his over-riding physicality and was sensational against France - even if an uncharacteristic slip in discipline let him down and cost his side dear a week later.
Captained his country during the warm-ups and was a vice-captain at Leinster under Matt O'Connor, but doesn't have huge experience in leading the team.
However, the Tullow man is a good ambassador off it who is more than comfortable in front of the cameras. As a product of the club system, his status would allow the union the opportunity to sell the game in non-traditional areas.
Perhaps the most concerning thing for Schmidt is the 28-year-old's injury profile and the concerns as to whether he'll be durable enough to lead his side as often as is needed.
Currently on the recovery trail after suffering an inner-ear problem, he has been plagued with different problems since the 2011 World Cup and has conceded that he's had to change his game as a result.
However, when fit he is one of the first names on the Ireland team-sheet and is a figure who is hugely respected by his opponents.
There is a lot to be said for the idea of Sexton being the captain of Ireland. On form, he is the country's most important player, a born leader who demands standards of those around him and a man who sets those standards high.
He is a senior man, contracted right through to the 2019 World Cup who, like O'Brien, would command universal respect from opponents.
Yet, coaches seem reluctant to over-burden him with the additional responsibility that comes with the figurative armband.
There is a sense that Sexton needs to be given space and time in international weeks rather than being exposed to the extra media duties and pressures involved in the captaincy.
Given his current struggles for form and his admission that the World Cup let-down has affected him, Schmidt may feel that he doesn't need to put any more pressure on his No 10's shoulders.
Sexton's half-back partner is also one of the first names on Schmidt's team-sheet and a senior player who has played at two World Cups.
One of the most consistent performers in the team, he is part of the leadership corps and is always heavily involved in the action and close to the referee.
A drawback for Murray is his lack of experience as captain. He has led Munster on occasion, but doesn't regularly have the team decision-making on his mind and has plenty on his mind as it is as he sets the tempo and tone for his team.
At 26, his age profile is perfect for this World Cup cycle, while he is likely to be a touring Lion again in 2017 whoever gets the nod to coach the tourists in New Zealand.
Ready to commit his future to staying, the captaincy could be a fitting reward for his talent and service but perhaps Schmidt will look elsewhere while retaining Murray as one of his chief lieutenants.
An outside bet, perhaps, but Henshaw will be 26 when the next World Cup comes around and the backline is likely to be constructed around him during the upcoming cycle.
A favourite of Schmidt's who leads the defensive line with a combination of courage and nous, he proved the team's most effective attacker at the World Cup as he carved France and Argentina open.
He will only get better too as he continues to adapt to the international game in the centre, while he may also provide competition for Rob Kearney at full-back after the emergence of Stuart McCloskey as a rival.
His position may negate his chances, however. Kearney is a leader of men, but has never been a realistic contender for the captaincy given his position removes him from the close-quarters action and means every visit to talk to the referee is a trek.
Many coaches prefer their captains to come from within the pack, a la Martin Johnson, O'Connell and Richie McCaw, but Brian O'Driscoll did a fine job from the centre when he had a respected pack leader in the Munster man inside him.
At 22, he may be deemed too young to take on the responsibility, but O'Driscoll was just 24 when he took over from Keith Wood.
Henshaw has the potential to be this team's talisman in the years to come. At the World Cup, he stepped up and delivered at crucial moments, but perhaps Schmidt will keep added responsibilities on the back-burner as he looks to develop the as-yet untapped potential in the Athlone native's locker.
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So, who will it be?
Schmidt is not short on options when it comes to picking a successor to O'Connell and will lean on all seven of the players named in this article in the years to come.
O'Mahony has long been seen as the long-term option, but injury negates his chances.
Heaslip's time may have passed and captaincy doesn't really suit him, while Murray and Sexton may be left to their own devices running the backline.
Henshaw will probably be happy biding his time, while O'Brien's injury profile will probably work against him.
That leaves Rory Best who appears the best option to take the team forward, at least until the Munster captain is fit and available to take over the role when he is ready.
Yet, Schmidt is fond of a curve-ball and will, no doubt, have thought long and hard about the implications of his decision.
Over to you, Joe.