England may be the only side remaining who can claim the Grand Slam, however the race for the Six Nations title is still well and truly open. France have suffered just the one loss in the 2011 tournament, going down to England in their last match, however the Les Bleus are never a team to be counted out.
Wales and Ireland are fighting the battle for third position on their own, with disappointing campaigns from Italy and Scotland once again seeing them trying to keep themselves from that dreaded ‘Wooden Spoon’ tag.
This weekend England face Scotland, Wales face Ireland and France will come up against Italy.
Tom Croft and Courtney Lawes are in contention for England's Six Nations clash with Scotland at Twickenham on Sunday after returning to the squad following long-term injuries.
England manager Martin Johnson said on Tuesday Croft and Lawes were in the frame for this weekend's Calcutta Cup clash and warned that he would not shy away from changing a winning team.
"It's good to get them back and see where they are," Johnson said of Lawes and Croft.
"We'll see how they go over the next day or so and make a choice from there. They're in the mix."
British Lion Croft has not played for England since fracturing a shoulder during last year's defeat against South Africa at Twickenham.
The blindside flanker's place in the England starting line-up has since gone to Northampton youngster Tom Wood, who has impressed after making his debut in England's away win over Wales in Cardiff.
Lawes, outstanding in last year's internationals against New Zealand, Australia and South Africa, has not played any part in the Six Nations after injuring a knee in January.
The 21-year-old Northampton second rower faces a fight to win his place back however, with locks Louis Deacon and Tom Palmer impressing in England's opening three Six Nations victories that have put them on course for a Grand Slam.
Johnson said the return of Croft and Lawes would intensify competition for places in the starting line-up, and said he would not hesitate to make changes if necessary.
"I think win or lose you're always going to pick the team that gives you the best chance of winning," Johnson said.
"There's always questions, always discussions about what we're going to do, how we can change, how we can get better. It's an okay place to be in at the moment.
"When (Croft and Lawes) come back the competition's going to be very fierce. Which is what you need in a squad.
"The more difficult questions we have at selection - with quality players forcing their way back into the team - the happier we'll be."
Injured captain Lewis Moody remains in doubt for the remainder of the campaign, with Johnson revealing that the Bath flanker's fitness was being monitored on a day-by-day basis.
Johnson meanwhile insisted England were not paying attention to bookmakers odds which have made them 1/14 favourites against the Scots.
"None of those bookies are playing," Johnson said.
"There's an expectation there and it gets out of hand either way.
"It's an easy game for them in a way. Everyone's talking about us but they'll come down and be desperate to get a win, to win at Twickenham, to beat England. If you start thinking 'Oh, they're not South Africa' you'll find yourself in trouble pretty quickly."
James Hook returns to the fly-half slot as Wales look to make it three wins in a row in the Six Nations tournament at the Millennium Stadium on Saturday.
Hook played at halfback and guided Wales to an impressive victory over Scotland at Murrayfield last month, but it was Stephen Jones who wore the No.10 shirt in the away win in Italy on February 26.
This time, Jones is on the bench, with fit-again Scarlets centre Jonathan Davies returning to midfield alongside Jamie Roberts after Hook deputised for him against Italy 10 days ago.
Another change from the game in Rome sees a recall for Cardiff Blues winger Leigh Halfpenny, who is preferred to the unlucky Morgan Stoddart, a try-scorer against England and Italy.
Wales coach Warren Gatland has otherwise kept faith with the team that edged the Italians and that means scrum-half Mike Phillips and No.8 Ryan Jones both will win their 50th caps.
The team announcement had been scheduled for Thursday to assess the state of various injuries, but Gatland brought this forward by 48 hours.
He will choose two from three back-five forwards - Rob McCusker, Andy Powell and Jonathan Thomas - after fitness checks on Thursday, while there is a confirmed place among the substitutes for Sale scrum-half Dwayne Peel.
Gatland will break the Wales coaching record of 35 Tests in charge on Saturday, eclipsing Alan Davies'mark. Ireland though, have only lost once in Cardiff since 1983.
"This is a crucial game for us as a win will keep us in the Championship mix and take us into that final round with everything still to play for," Gatland said.
"But it is also a big game for Ireland, who are in a similar position to us going into this match."
Addressing the fly-half issue, assistant coach Robin McBryde challenged Hook to justify the faith shown in him.
McBryde said: "The debate at fly-half will continue long after the Championship is over, but we have gone for James on this occasion.
"James provides a running threat and we will be looking for him to show he can control the game as well and help us play in the right areas."
Of Halfpenny's recall, McBryde added: "Leigh had a good run out for the Blues at the weekend, we know all about his pace and what he offers around the field as well as being solid under the high ball and giving us a long-range kicking option.
"Morgan misses out, but he has done nothing wrong and we know he can be relied on if we need him from the bench."
Ireland coach Declan Kidney named an unchanged side on Tuesday for this weekend's crucial Six Nations meeting with Wales at the Millennium Stadium.
Kidney has kept faith with the side which defeated Scotland 21-18 at Murrayfield last month, as the Irish aim to score their third consecutive away win in Cardiff since 2007.
Ireland, who beat Italy in their opening match before suffering a home defeat to France, need to win on Saturday to keep alive their hopes of winning the Triple Crown.
However Kidney warned his team to expect a ferocious battle against a Welsh side who have shown signs of improvement since following up their opening defeat to England with away wins over Scotland and Italy.
"There's not a whole lot between us," Kidney said.
"Going to Cardiff is always a daunting task. I know we're in for a huge game.
"Two years ago there was one kick of a ball between us. At this level and with the fact that the two teams know each other so well, space is going to be at a premium.
"It will be one of those games that whoever takes their chances will come out on top."
Ireland captain Brian O'Driscoll meanwhile said he had disregarded the latest betting odds, which have seen Wales installed as favourites.
"We don't pay too much attention to who's favourites or underdogs," O'Driscoll said.
"Both sides have had mixed form; everyone's aware that if both sides click they are capable of playing decent rugby.
"We're not far away from clicking. I don't think either side will buy into who is the favourite or underdog at the moment."
France coach Marc Lievremont made three changes to his starting lineup on Tuesday when he named his side to play Italy in the Six Nations in Rome on Saturday.
Two of those were in the pack where Castres flanker Julien Bonnaire replaces Imanol Harinordoquy and Sylvain Marconnet returns at loose-head prop taking over from Thomas Domingo.
Maxime Medard, who missed the 17-9 loss to England at Twickenham due to injury, comes in at full-back for Clement Poitrenaud.
The biggest surprise was with the dropping of Harinordoquy, who is widely regarded as being one of the best back row players in the world, and the retention of Racing Metro powerhouse Sebastien Chabal, who played poorly against England.
Chabal "has my full confidence" the coach said, adding that he failed to understand all the criticism that was levelled against him and winger Yoann Huget after the England game which wrecked French hopes of back-to-back Six Nations Grand Slams.
On the two changes made to the pack Lievremont said: "We are trying to change things a little, to give playing time to others, but at the same time to keep some kind of consistency in our approach.
"On top of that we have to take into account the fact that some players were more involved than others in domestic league games last weekend."
France opened the tournament with wins over Scotland and Ireland before the crushing defeat to England and will travel to Wales after the game in Italy.
"It's frustrating for us to see England going for the Grand Slam but we must stay in the tournament and aim for an honourable finish," Lievremont said.
"Playing away to Italy is never that straightforward. We have handled them well in the last two years, but we saw that the Italians came close to defeating both Ireland and Wales.
"If they lose against us they will be playing for the Wooden Spoon against Scotland, so we know that they are going to be full of determination."
Scotland defence coach Graham Steadman says his side must make improvements in Sunday’s RBS 6 Nations Championship clash with England at Twickenham.
In an exclusive audio interview, Steadman expresses his frustration at the “soft tries” Scotland have conceded in each of their three tournament fixtures to date, but testifies to a “real belief” around the squad ahead of Calcutta Cup battle.
He said: “The biggest thing for me is our forwards fronting up. Get that right and we’ll lay the platform for the quality we have in the backs.
“There’s a confidence that we can go out there and win. England are three from three, playing with a lot of confidence, but within our squad, everyone has stuck together and is very upbeat. Scotland thrive on being underdogs and that is very much the case this weekend.”