Penrith young guns Tyrone May, Dylan Edwards and Liam Martin know all too well how a season of dominance can be obliterated in the blink of an eye.

Especially on the biggest day of the NRL calendar at ANZ Stadium.

Penrith’s junior systems have rightly been the centre of attention in grand final week.

How three distinct groups in Sunday’s grand final side dominated junior age groups and made them one of the most successful teams of the now-defunct Holden Cup.

But the forgotten story is that of the title that got away in 2016.

Penrith dominated that season, despite Nathan Cleary and James Fisher-Harris both being eligible but spending most the year of first grade.

They went on an undefeated run of 16 games, and even with Jarome Luai suspended for the decider against the Sydney Roosters they were clear favourites.

And at 28-6 up at halftime, the result looked a foregone conclusion.

“But halftime we didn’t want it to come,” May told AAP this week.

Forty minutes later and it was 30-28.

Joey Manu scored a double and the Roosters had won, meaning Penrith’s record-breaking season amounted to nothing.

“We just let them get on a roll,” May said.

“The lesson is momentum. You have seen what momentum has done in this finals series, it comes and goes.

“It’s about how we handle that this Sunday because the Storm are red hot.”

Under-20s football is very different to the NRL, but there is one lesson May has taken from that game.

Preparation must be meticulous in grand final week, and you can’t let your guard down for a second.

“There was a play there that all week we did,” May said.

“Ciro (coach Cameron Ciraldo) gave us a tip, they are good at trapping and scrapping.

“I went to put in a grubber, Victor Radley traps it, scraps it and Johnny Tuivasa-Sheck picks it up and scores. That was the play that won them the game.

“That one still stings for me because I was the one who kicked the ball. The whole week we spoke about it, it was just stupid.”

Others have preferred to wipe the memory headed into this weekend.

Edwards for example missed a penalty shot with just minutes to go to make it 30-30, but would rather not think or talk about the game.

“I don’t think (you take much from it), it was a while ago,” he said.

“We have learned so many lessons in the past two years playing grade.

“I haven’t watched it back, I really don’t like thinking about it. So yeah, it does still sting.”

Regardless, Penrith’s junior experience is certain to come in handy against Melbourne on Sunday.

While just three of their team have featured in a NRL decider before, an extra nine have played at ANZ Stadium on grand final day in under-20s or reserve grade.

“A grand final regardless of what competition you are playing in is an elevation from the average game,” coach Ivan Cleary said.

“Particularly at NYC level when back in those days you were part of the big day. All these experiences can’t hurt.”