Who’s in charge?

Joe Schmidt, once an assistant coach to Vern Cotter at Bay of Plenty in their native New Zealand and then at Clermont-Auvergne in France. He struck out on his own in 2010, becoming head coach of Leinster - a position he left in mid-2013 to take charge of Ireland in succession to Declan Kidney. Led his team to the Championship in 2014 and 2015, securing the title last year with a final-day victory at Murrayfield against Cotter’s Scotland.

Encouraging World Cup?

Up to a point - the point in question being the quarter-final against Argentina, in which they were blown away. Before that 43-20 defeat at the Millennium Stadium, however, they had played some excellent stuff in the pool stages, putting 50 points on Canada in their first match then running up 44 against Romania in their second. They toiled against Italy, only winning 16-9 against a team who were inspired by the return of their captain, Sergio Parisse. Nonetheless, that result ensured qualification for the quarter-finals, and they went on to top the group by beating France 24-9.

How are they looking now?

Having successfully defended the title last year, Ireland should go into the Championship with some confidence. They know what it takes to win big games, and did particularly well to claim their second successive crown last year, when they had to rack up a big win in their last game against Scotland then hope that England did not better their points differential.

However, the post-World-Cup retiral of Paul O’Connell, their captain and lock forward, has left them short of leadership. What is more, that defeat by Argentina continues to haunt them, as does the poor European record of their provinces this season. Could they really be on the way down? They are aware that it is, at the very least, a question they will have to answer.

Who’s in, who’s out?

O’Connell, one of the finest players ever to represent Ireland, is the biggest departure, but Schmidt also has a worryingly long injury lost to deal with. Tommy Bowe, the Lions winger, is out after knee surgery late last year. Props Cian Healy, Marty Moore and Mike Ross are also unavailable, as are locks Iain Henderson and Dan Tuohy and flanker Peter O’Mahony.

Jonathan Sexton, the Leinster fly-half, was a serious doubt last month after being taken off with a head injury during his team’s Champions Cup defeat by Wasps a couple of weeks ago. Sexton also missed three months’ play last season after a series of head knocks, and there were calls for him to consider retiring on safety grounds. However, he was passed fit last week, and Schmidt branded those calls “disappointing”.

Ulster hooker Rory Best has taken over the captaincy, and Schmidt has chosen four uncapped players in his extended squad for the tournament - centre Stuart McCloskey, lock Ultan Dillane and back-row forwards Josh van der Flier and CJ Stander.

Where are they strong?

They are a richly experienced squad who have a proven ability to finish with their noses in front in big games - at least against most other European teams. Best and flanker Sean O’Brien - who was widely considered as an alternative for the captaincy - have been there and done that and got the medals to prove it. Among the backs, Keith Earls and Rob Kearney have also been over the course, while fly-half Jonny Sexton, if fit, is always a potential matchwinner.

Where are they weak?

The retirals of first Brian O’Driscoll and then O’Connell in recent years have deprived them of two of rugby’s greatest ever players. A relative decline from the heights enjoyed when those two were in their pomp is unavoidable. Injuries have also stretched their resources, while other players have been off form domestically and do not look in good shape going into the Championship.

Key player

Jonny Sexton. Although he was passed fit to play in the wake of the head knock he took against Wasps, there remain doubts about the 30-year-old’s long-term fitness. On his day, he is the best playmaker in the tournament. Without him, Ireland will struggle to find their rhythm.

Who will they be worried about?

Wales. It may be too early to call this Sunday’s match at the Aviva Stadium the meeting of the champions and champions-elect, but it is nonetheless a fixture that could go a long way to determining the destination of the title. Lose to the Welsh and Ireland will have lost control of their own destiny. What is more, they then have only six days before their second game - at the Stade de France against opponents who might well have been given a significant boost to their morale by winning against Italy in their first match.

In other words, it could be a long and difficult season for Ireland unless they get it right first off. They are away again in round three, when they visit England, and by the time they get round to playing what should be their two easiest matches, at home to Italy then Scotland, they may be out of the running and have nothing to play for other than the minor places.

What will they be happy with?

A decent, hard-fought defence of their title. Schmidt has already sought to downplay expectations by declaring that a top-half finish would be a good outcome for the team.