In a week of considerable tension, both Andy Farrell and his French counterpart Fabien Galthie can take comfort from the fact that their path to the Six Nations title is at least clear, if not easy.

It's the easiest possible brief for Galthie's France, who can end a 12-year drought with any form of win over England in Paris.

For Ireland their hopes hinge on an English victory following a home win at the Aviva Stadium - a result which would see Farrell's side clinch the Triple Crown regardless of events at the Stade de France.

As far as the title race is concerned, the margin of victory in either Dublin or Paris is irrelevant.

Even if the two sides do finish level on points - an outcome that will only occur if Ireland win without a bonus-point and France draw with England - Ireland's superior points difference would see them claim the title.

In nerve-shredding weeks like this small mercies are gratefully received, and both head coaches will be mightily relieved to have known from the very start of this week exactly what needs to happen in order for the title to be theirs.

It isn't always this easy - 2015, anyone?

Seven years ago the final day's match-ups mirrored those we will see this Saturday. The games took place between the same teams in the same order - albeit at different venues - with each one threatening to send the title to a different nation.

England went into that day top but ahead of Ireland and Wales only on points difference, and the required outcome for each team would only be determined by the result of the previous match.

Wales, third going into the day, knew they had to rack up a massive score against Italy before hoping Scotland and France would win or at least keep the scoreline tight against Ireland and England respectively.

Warren Gatland's side held up their end of the bargain with a second half blitz at the Stadio Olimpico, where they only led 14-13 at the break before running in seven tries after the interval to increase their points difference by 41.

The result put them top. At Murrayfield, Ireland went through their preparations not knowing precisely what was required until the final whistle sounded in Rome.

They discovered they needed to beat Scotland by at least 21 points to keep their title hopes alive and eliminate Wales by doing so.

"It was just very strange," Johnny Sexton said this week, recalling the situation in the dressing room before the game.

"[Former head coach] Joe Schmidt coming into the dressing room and saying 'we need to get this amount of points' and you're going 'oh God'."

Sexton is one of six Irish players to remain in the squad having been involved back then.

They knew the minimum amount of points required to stay in the title hunt, but with England still to come against France, they had no idea of the golden number.

"It was one of the most bizarre days of my career," said Sexton.

"One of the most special, though. It came down to small margins like Jamie's tackle."

Jamie Heaslip's late tackle - dislodging the ball from Stuart Hogg's grasp as the Scotland full-back dived across the try line for what would have been no more than a late consolation score - proved to be the difference between Ireland winning and losing the title.

But they didn't know that yet. A 40-10 victory ensured they were top of the table with one game of the tournament remaining and the retention of their title was in sight.

However, England could still pip them by securing a 26-point winning margin over France.

"We were delighted when we finished the game but it was like a nervous excitement, it wasn't a celebration," Iain Henderson, who came off the bench on that day, remembers.

"It was like a 'right, we've done that but it's not done'."

Inside a Murrayfield suite the traditional post-game presentations began with players and coaches present in body alone. Events at Twickenham were now front and centre.

"They were giving post-match speeches and the presidents were chatting and presenting the refs with a corner flag, all the official stuff was happening but no-one was watching any of it. Everyone was just watching the screen," Henderson said.

What unfolded in London was one of the most chaotic, remarkable games of rugby that would be remembered had it stood alone, let alone coming as the climax to an extraordinary title race.

Twelve tries were scored as England put up their highest-ever total against France while the visitors became just the second team in the competition's history to score more than 30 points and lose.

The final minute arrived with England a foot away from the line, needing a converted try to win the championship.

"I remember towards the end France went to try and play it out of their own in-goal area and there were gasps everywhere," said Henderson.

"A handful of pints had been taken at that stage and the excitement was through the roof. At the end of it I think it was Rory Kockott who booted the ball out of his own goal-line after they'd tried to run out a time or two.

"Then the place just erupted."

Ireland won the title courtesy of a +6 points difference over England, claiming back-to-back championships at the end of the most jaw-dropping day of sporting drama that went some distance to furthering the Six Nations' claim to being rugby's best competition.

This weekend's action will not replicate what we saw in 2015 with winning margins not holding any relevance.

Still. There is a title on the line. And two coaches seeking their first piece of silverware, not to mention fascinating opposition in the face of a Scotland side with a point to prove and an England side out to build on what was at times a heroic 14-man performance last week.

Ireland and France fans won't need their calculators. But they still may well need a good sofa to hide behind.