You won't get far against South Africa without a lineout, and the fear in recent months was that Ireland were struggling to get that setpiece going.
To look back across the summer and the World Cup opener against Romania there were plenty of issues.
Frustratingly, the virus that had infected their lineout had multiple symptoms.
Sometimes it was the throwing, other times they would mistime the lift and on some occasions they were simply too easy to read.
Winning the lineout wasn't the only issue.
In the warm-up games against Italy, England and Samoa they were struggling to use the lineout to launch attacks, with their mauls consistently either being held up or penalised for obstruction.
Saturday's eight-try win against Tonga in Nantes would indicate that Ireland have straightened out their lineout issues, albeit against limited opposition.
With 21 lineouts out of 23 won on their own throw and the two errant restarts coming with the game long won, it was a sharp and snappy effort from the pack, while they even showed some innovation in their maul as they shifted the point of the attack for Caelan Doris's score in the opening half.
"Sometimes you don't know exactly how it’s going to go, those little trick plays, but we drilled it well all week and it worked, so we’re happy enough with that," lineout caller James Ryan said after the game.
"There was good variation as well. We had a couple of drives and peel, and obviously played off the top as well. It was good, so we’re happy enough with it.
"It was good tonight. We got a little unlucky with a couple of things last week, so we didn't reinvent the wheel or anything this week, we just trusted what we do well and it came off tonight. We're delighted.
"We love getting a maul try, we love getting those tries as an Irish pack. We put some decent pressure on their lineout as well so we’re happy enough with how it came out."
Whether right or wrong, when a lineout fails it's the hooker who feels the brunt of it, but Rónan Kelleher showed no signs of feeling the pressure in his first start since the end of February, with a 100% record off his 11 throws during the opening half.
"As we've been saying, we’ve just been working on a few little tweaks here and there," the Leinster hooker said.
"Not that we’ve been bad, but we’ve been really trying to focus on ourselves. Yeah, it was good to see that, all that work kind of pay off.
"The forwards did the job to make sure they were max drilled each time. It made our job a lot easier as hookers.
"It just makes everything a lot easier when that is going, it just allows you to get into your game, get into your flow a bit more. It was great."
Ireland showed a good degree of variety in their lineouts, both in terms of the size and target, varying between five, six, and seven-man lineouts, and bringing the likes of Conor Murray and Bundee Aki into the line on occasion.
And although Tonga contested very few of Rob Herring's second-half throws, they did send jumpers up into the air on several of Kelleher's efforts, but came away fruitless.
However, the Leinster man knows the likes of Eben Etzebeth, Franco Mostert and RG Snyman will be much harder to avoid in Paris this week.
"Absolutely it will be a step up. For us, we've come in and are focused on this game, it was a physical game, we’ll recover, we’ll review it, and see what we need to work on. And we’ll look forward to that," Kelleher added.
As well as their setpiece strength, the world champions will be bringing the game's meanest defence to Stade de France on Saturday, having conceded just one try and 10 points total across their last three games.
And Ryan says they've perfected the "outside-in" defence, shooting up with a narrow defensive line and cutting off the opposition's ability to get the ball wide.
"They're the masters of it," the Ireland lock added.
"Tonga did a little bit of it tonight, they came off the line hard but they are the best at it definitely. So we’ve just got to be nice and calm when that pressure comes on to us. But it’s easier said than done, we’ll have to look at it during the week and have a pretty proper plan in place to deal with it.
"They play a big pressure game. Obviously they've a very strong setpiece; lineout and scrum, it’s kind of their DNA. Defensively, huge line speed, more pressure.
"They’re kind of a pressure-based team, they try to get after teams in as many parts of the game as possible, so our biggest challenge for a long time."
Watch live coverage of Ireland v South Africa (Saturday, 8pm) on RTÉ2 and RTÉ Player, listen to live commentary on RTÉ Radio 1, and follow live updates on RTÉ Sport Online and the RTÉ News app.
