It was a long time coming, but this year, finally, Limerick shattered the most enduring mould of Munster football. But that's not quite enough. Tomorrow in Mullingar, they contest the All-Ireland under-21 final against Tyrone, and they want to defy the odds and win the thing outright.

That might sound like a joke. Cork, Waterford and Westmeath all wish it was. Each of them fell victim to this Limerick momentum that, before now, had always been severed well short, leaving them dreaming of the impossible.

This season though, has been historic from the start. It began with victory over Cork, who along with Kerry, had won every Munster title since the inaugural championship in 1964. And that didn't come easy. At Pairc Ui Chaoimh, they trailed Cork by four points early in the second half but clawed back to win by the minimum.

A tense Munster final saw them bypass Waterford and then, a little over two weeks ago, Westmeath felt their force. A drizzly Portlaoise was illuminated by their sheer determination and the All-Ireland title holders crumbled. So their arrival in Mullingar must rank as the one of the most significant breakthroughs in championship football in recent decades, and trying to explain it doesn't come easy.

Standing in front of it all is manager Liam Kearns, who took over the job as senior Limerick manager six months ago and decided to incorporate the under-21 role as well. It wasn't all his planning, but 10 of the under-21 players are also in the senior side and he sees the two roles as going hand in hand.

"At least six of this side played competitive senior football before they played under-21," he says. "That has a bit of a bearing. That there are the three lads playing senior competitive hurling helps as well. They're all able to look after themselves at that level, so when they came back to under-21 level, it does get a little easier and the experience stands to them."

The roots of success, however, have been dug a little deeper, with some changes coming into the overall Limerick approach in recent years. Most significant has been the five-year plan in football and hurling, with most of the current players coming out of that system. That helped bring about two Munster finals at minor level - in 1997-98 - but they lost both.

"There have been some big changes since those minor years," says Kearns. "Brian Begley used to play centre back, Mark O'Riordan and Michael Keogh never played minor at all, and Jason Stokes was at full back. They've all improved and grown as players since and that's been the making of this side.

"They're a good group of players and they've come together at the right time. If we can keep them together then there is definitely a future at senior level. More importantly, there are 13 of this panel under-age again next year so there is surely the basis of a reasonable side again next year."

It might take a couple more years to start making some noise at senior level but Kearns believes the Limerick County Board have a role to play. "They have to build on this and make sure they don't go back to what they were doing before this achievement."

As for this year, the victory over Cork was the strongest catalyst, and Kearns has been half expecting everything after that. "I was hopeful of beating Westmeath and Waterford, but Cork was the real one, that gave us the belief. Nothing was a shock after that and the confidence just grew."

Tomorrow, they come up against a Tyrone side that have done just about everything right at under-age level in recent years. The bones of this team comes from the All-Ireland minor success of two years back, and Kearns knows well the sort of talent he's coming up against.

"Tyrone have been favourites for this title from the start and deserve to be, but I have an awful lot of faith in this team. I know they'll give it everything until the end. Everybody here is rooting for us but nobody believes we can actually finish it off. All the players are fierce determined to do that."

Physically, they will match Tyrone in every area. Full forwards don't come any bigger than Begley - one of the three dual players along with Stephen Lucy and Brian Geary. But Kearns puts equal emphasis on talent and hard work - believing as much in the intelligent player, one that can see what has to be done.

"We have quite a few leaders on the pitch. And I just hope the team will perform like they're capable of, like any team in their first All-Ireland final. After that, you can only hope that it will be good enough to win. But we definitely have size where it counts and pace where it counts."