Such a CV gives the Englishman a unique view of this match, a World Cup opener that will likely go a long way to deciding the fate of either side.

Win, and you may already know your quarter final opponents, lose - and a potentially huge game against Japan awaits.

So, Dan, what's going to happen?

“I don't know what will happen on Sunday, to be honest!" he smiled, at the launch of the Guinness Pro14 in Dublin.

If the game is loose and open, then Scotland are so dangerous... but Ireland know that and my guess is they will look to squeeze them at set piece.

“Scotland's set piece has improved over the last number of years, so if they can hold them there and get a bit of counter attack in the game, maybe they can do well, but Ireland have got to go into the game as favourites - naturally, they would do.

“But you just never know, the weather might have a play on it. That would be really disappointing.

"I'd love to see Stuart Hogg running back and Finn Russell throwing those missed passes out and Ireland defending those – then some big ball carries from the Irish forwards, and whether Scotland can match that – which they did the last time they beat them [in 2017]."

That day in Murrayfield became infamous for Joe Schmidt's complaint that the team bus was slightly delayed. How will he deal with a massive rainstorm that's predicted for this weekend?

“On balance I'd say Joe would probably be happier with the rain [than Gregor Townsend]," McFarland said. "Scotland do have a really good kicking game, they've got some long boots in there – Finn can kick a long way, Hogg can kick it – territorially they can take advantage of poor weather when you don't necessarily want the ball.

“But Joe puts a premium on possession, and in the wet weather that's when you need to keep the ball...”

Ireland have lost just once to Scotland since 2013, with eight wins from their last 11 meetings in total.

They're short odds to add to that wining tally on Sunday against an unpredictable Scottish side, who won three of their four World Cup warm up games.

Their last competitive game was a confusing one, though, turning a 31-0 deficit in Twickenham into a 38-31 lead, before seeing the game end as a draw.

What is the real Scotland?

“There was a lot of talk of the 'huge change' in way they played in the second half in London, but I don't buy that,” McFarland said.

“They more or less played the same way in second half, they just did it better. They kicked poorly in the first half, but in the second half they were just much better at kicking the ball.

“A little bit of confidence going out there, which might be unusual, but they had nothing to lose.

“They didn't throw everything to the wind in the second half, but I thought it was remarkable how they got back on their feet after being knocked down by England.”

Three of McFarland's Ulster squad are likely starters on Sunday morning, with Rory Best, Iain Henderson and Jacob Stockdale pushing to start.

Best and Stockdale have endured mixed warm ups – with the skipper receiving some public support from his coach, while the winger showed he could back himself after a mixed day in Twickenham – with a solid two-try performances against Wales.

“Jacob deals with pressure very well, he's a confident young man and I think he's a class player, he's a real difference maker,” McFarland said.

“The kind of tries he scored for us last year, like Racing at home, they're what you need at that level, if you're going to beat a team like Scotland or win a quarter final, you need people who can do something that's a bit different.

“He was exceptional in his last game with Ireland, you could see it in him, he wasn't as happy in Twickenham with his own performance, but backed it up with that real competitive edge and showed something special.”

Henderson will have plenty to show in Tokyo too, with Ireland's lineout under serious pressure – especially with Devin Toner left at home.

“They're broad shoulders,” McFarland said of his second row. “He's a good player, with James Ryan there as well, they're two excellent players. There is a little pressure there, I suppose, the lineout hasn't been the best thing but I back them to solve those issues.”