The Six Nations comes to a grandstand finish on Saturday with Wales chasing a Grand Slam and England and Ireland hoping to snatch the title from them.
Wales will wrap up the title and complete their first tournament clean sweep since 2012 if they beat Ireland.
But defeat in their 14:45 GMT match in Cardiff would open up the title race.
Barring an improbably emphatic Ireland victory, England would lift the title by beating Scotland but a Scottish win would see Ireland retain the trophy.
Wales are aiming to land their fourth Grand Slam of the Six Nations era, with two already won under coach Warren Gatland, who is leaving his post after this autumn’s World Cup.
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Gatland’s side are also looking to extend their national record-breaking winning run to 14 successive Tests.
If they fail, both England and Ireland are poised to post impressive statistics of their own.
England can lift their third title in four Six Nations campaigns under Eddie Jones, while an Ireland success would be Joe Schmidt’s fourth in six years in his final year as their coach.
‘What the hell is Eddie doing?’
The three-way tussle for silverware has prompted a testy pre-match exchange between the title-contending coaches.
England coach Eddie Jones, asked for his views on Wales’ meeting with Ireland, said that Wales are “definitely tiring”, adding that “they have made more tackles than anyone else in the tournament”.
“What the hell is Eddie Jones doing talking about our game?” said Gatland when those observations were put to him.
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“If you look at the stats England have made a hell of a lot more tackles than us in this tournament.
“My advice to Eddie is to concentrate on the Scotland match.”
Wales have made 660 tackles so far in the tournament compared to England’s 793.
England forwards Tom Curry, Mark Wilson and Jamie George, with 76, 71, and 67 tackles respectively, have made more tackles than any other player in the tournament.
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Meanwhile, Schmidt suggested on Thursday that Wales broke Six Nations protocol by going direct to the tournament organisers to ask for the Principality Stadium roof to be closed on account of forecast heavy rain.
The roof can only usually be closed if both teams agree. It was announced on Friday that the game will be played with the roof open at Ireland’s request.
“It’s our stadium and we should be able to do what we want with it,” said Gatland.
Permutations in full
- A Wales win would give them the Six Nations title and Grand Slam. An additional three points are awarded to Grand Slam winners, which would put Wales out of England’s reach
- A draw for Wales would be enough to win the championship if England lose. If both sides draw, England would win the title if they earn a bonus point and Wales don’t
- If Wales and Ireland draw and England win, Eddie Jones’ side would be champions
- Ireland will be champions if they win and England don’t
- Should Ireland secure a bonus-point win over Wales and England beat Scotland without scoring four tries, the two teams will finish level on 19 points. Points difference would then decide the championship: England currently lead the way with 83, compared to Ireland’s 19
Predictions from BBC Radio 5 Live pundits
Former England scrum-half Matt Dawson: “Super Saturday is my favourite international weekend of the year but I think Wales might well nick the Slam.”
Former Ireland wing Shane Horgan: “It’s too early to say whether Ireland have recovered from the early setback against England. Wales.”
Former England fly-half Paul Grayson: “I didn’t back my instincts and got it wrong in round one so I’m going to go with my gut. Ireland win in Cardiff so England win the title.”
Former Wales fly-half Jonathan Davies: “Home advantage will see Wales sneak it.”
Scotland seeking end to Twickenham hurt
Saturday will be the 137th staging of the oldest Test in the sport with England and Scotland meeting at Twickenham 148 years on from their first encounter.
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But Scotland will be more concerned about recent history.
It is 36 years since they have won away to England, while their last visit ended in a 61-21 reverse that matched their heaviest defeat against their oldest rival.
England have scored 19 tries in the tournament so far, more than any other team. However, Jones has warned Scotland that they are yet to reach their potential.
“We’re nowhere near our best, we’re just slowly getting there,” he said. “But we’re going in a great direction.”
Despite a lengthy injury list, Gregor Townsend’s side will take heart from a stirring Calcutta Cup victory at Murrayfield 12 months ago when England were spectacularly upset.
“If no-one thinks we’re going to win then that’s fine,” said Townsend.
“We believe we can win and that’s what we’re working to do. Scotland teams tend to be underdogs on a number of occasions and it usually brings the best out in them.”
Stick at 21?
Saturday’s Six Nations gets under way at 12:30 GMT with a match between two desperately out of form sides, Italy and France.
Italy’s 57-14 defeat by England in the last round was a record 21st successive defeat in the Six Nations. Their last victory in the tournament against Scotland in February 2015. and they are already assured of the Wooden Spoon.
But France are also enduring a miserable run with just two wins in their past 11 Tests.
After restricting Six Nations leaders Wales to a 26-15 scoreline in Rome and leading Ireland at half-time of a 26-16 defeat, coach Conor O’Shea is hoping for a third strong home performance of the campaign.
“Our focus will be on ourselves, trying to play our best rugby. We want to finish the championship with a great performance at Stadio Olimpico,” he said.