He was at the helm the last time New Zealand and South Africa met in a Rugby World Cup final.
That 1995 final was 28 years ago but it still stirs some deep emotions in rugby fans of a certain vintage.
History will record South African first five Joel Stransky landed a drop goal in extra time to seal a tense 15-12 win for the Rainbow Nation.
The All Blacks had been utterly dominant during the tournament but a bout of food poisoning 48 hours before the final and an inability to adjust tactics saw the team trip at the last hurdle.
Mains was at the centre of claims suggesting the food poisoning was not accidental but none of that made its way into the script of Invictus — the movie made about the tournament.
That colourful back story has helped add fuel to what shapes as a tense final on Sunday morning (New Zealand time).
But any talk of revenge was a big stretch, Mains said.
"That was nearly 30 years ago ... and I doubt very much the All Blacks will be using that as motivation," he said.
"They’ve got their own culture and own triggers inside their team, and that is what they will be using to get up for the match."
The All Blacks’ World Cup prospects were seemingly dented by South Africa when the Boks thrashed them 35-7 at Twickenham just prior to the tournament.
The 27-13 loss to France in the opening game was seemingly further evidence the class of 2023 were not championship material.
However, Mains dismissed the loss to the Boks.
That was a warm-up and everything which could go wrong, did go wrong, he suggested.
"That game against France was a tough encounter, though. But I believe it gave the All Blacks an opportunity to identify where they needed to strengthen their play and also gather confidence to use the advantages they’ve got in their personnel better than they had been using them."
The All Blacks strung together impressive wins against Namibia, Italy and Uruguay before overcoming world No 1 Ireland in an epic quarterfinal.
They then brushed aside Argentina 44-6 in the semis.
South Africa edged France 29-28 and England 16-15 in the playoffs to make it through to the final.
Arguably, the Boks had to spend more energy to get to the final.
But their combative style, and an ability to go wide if they choose, will present the All Blacks with a lot of challenges.
But Mains is predicting a six-point win to the All Blacks.
"Jason Ryan really has got this forward pack playing at its full potential, and that is where there has been the most significant improvement.
"And when you get your forwards playing well, and getting a bit of go-forward, it gives your backs the opportunity that they needed.
"The rhythm in the backs has certainly improved as well, so Joe Schmidt has got to take some credit for their tactics and the way they are doing that."
Head coach Ian Foster also came in for some praise for identifying where he needed help and by allowing others to take the lead in certain areas.
