England
After the autumn, New Zealand and a couple of good performances and evenly matched games against Australia and South Africa, England have to be favourites for the tournament. They were very difficult to play against last time and have developed a modern, mobile tight five. England's win against the All Blacks gave the entire Six Nations extra kudos but they are far too bright these days to bask in their own glory.
The loss of Manu Tuilagi for the opening game – or games – is a blow but that is offset by Tom Wood's return to his form of 2011 against Wales. He sticks all the parts together. Joe Marler for the injured Alex Corbisiero gives more in the loose, if not at scrum-time. Ben Morgan is ball‑carrier-in-chief while Dan Cole is not simply an aggressive tighthead prop but a real force at the breakdown.
Ireland
Some famous names are missing, but change has brought some exciting combinations – none more than in the backs, where the new boys Simon Zebo and Craig Gilroy come in outside the Brian O'Driscoll-Gordon D'Arcy centre partnership – starting for a 48th time. O'Driscoll's knowledge should reduce the tries Ireland concede – 13 last time.
Elsewhere Mike McCarthy and Donnacha Ryan start in the second row together for the first time in the absence of Paul O'Connell, one of those rare locks who never seems to make a mistake.
Tactically, both half-backs are good counters and will look to overload the short side. Remember it takes four defenders to defend a short side against three Irish attackers because the scrum-half makes the extra man. From a breakdown that is how Conor Murray likes to play it. From more broken play, say following a line-out, look for the fly-half Jonathan Sexton to go back against the grain in the second or third phase if the numbers work out.
Scotland
No one really knows what to expect from the new coaching team but Scott Johnson has picked big men and we know that any pack fashioned by Dean Ryan will be organised and have a touch of steel about it. We also know that Johnson is a fan of Mark Ella, one of the greats of Australian rugby and a fly-half famous for saying something along the lines of "if I touch the ball twice in a move, we are likely to score; if I touch the ball three times, I'll score."
So, look for the returning fly-half Ruaridh Jackson to get heavily involved, looping once or even twice in a move in an attempt to work the wings Tim Visser and Shaun Maitland, the former Crusader, into space.
Defensively Saturday will also be interesting because both teams like the blitz defence, which tends to be high risk but high reward – as Scotland showed with their intercept try against the All Blacks.
France
The form team after the autumn Tests and the side which will benefit most from the ruling which insists on two props being among the replacements. While some sides struggle to find quality for the bench, France have a legion of big men – and not so big men – who can do the job.
Against Australia in November, Philippe Saint-André replaced both props and the hooker with the Clermont Auvergne front row on 60 minutes and they just pushed the Wallabies around, earning a penalty try to go with the one set up for Louis Picamoles in the first half.
The lineout, with its multiple targets, is not bad either but I will be interested in the return of Thomas Domingo after surgery on both his knees. When Domingo plays, France tend to win. Otherwise there is the explosive, ball-carrying power of the No8, Picamoles.
Italy
A sign of the times perhaps but after 13 years there is no Bergamasco brother in the Italian squad as the head coach, Jacques Brunel, continues to expand the style of play.
A pack with Martin Castrogiovanni, Leonardo Ghiraldini and Andrea Lo Cicero at the front and Sergio Parisse at the back is always going to be influential, but Brunel has ambitions for a wider game and in the autumn came close to beating Australia. However, Rome was not built, etc … and the Brunel overhaul will take time and will not be entirely successful until a world-class kicker is found – something the team sorely needs.
Last season barely half the kicks went over. That said, Brunel has stuck with the squad from the autumn, he has three home games and Tommaso Benvenuti is developing as a centre with a touch of class.
Wales
Wales' attacking game withered in the autumn, writes Paul Rees, but with six of the back division that played in last year's grand slam in residence for the start of the Six Nations, they have spent the past couple of weeks working on ways of bringing their dangerous back three into play.
They have opted not to pick a second first receiver behind, an indication they will try to blow a hole in defences rather than unpick them. With precious few tries scored at international level from phase play, they have been focusing on scrums and, especially, lineouts where Aaron Shingler will be a target at the back, providing the means for the No8 Toby Faletau to charge at the Irish backs.
The Wales attack coach, Robert Howley, has pointed to the experience Ireland have at 10, 12 and 13, and a follow up to Faletau targeting the outside-half Jonathan Sexton would be one of Wales' big wings, George North and Alex Cuthbert, coming into the midfield at pace and heading towards the centres Gordon D'Arcy and Brian O'Driscoll. Quick ruck ball – Ireland do not have a foraging No7 – would allow Wales to seek space outside for the likes of Jonathan Davies and Leigh Halfpenny.
Wales were slow in thought and deed in the autumn, except for a period in the second half against New Zealand, but speed will be the watchword this tournament.
guardian.co.uk