JIM McGuinness has flashed out a warning that will strike fear into the hearts of contenders for next year's All-Ireland football title by claiming that Donegal have reached only two-thirds of their potential so far.
If he's right and they were still good enough to win an All-Ireland, plus successive Ulster titles, over two seasons in which they powered to 12 wins from 13 championship games, then the future is all gold for Donegal, even if they have to share their manager with Celtic next year.
McGuinness also insists that far from reducing his focus on the challenge of pursuing the All-Ireland double, his new job with Celtic will enhance his contribution to Donegal.
Speaking in New York, where he will manage the 2012 football All Stars against their 2011 counterparts in an exhibition game in Gaelic Park tomorrow night, he said that he hopes to learn from working closely with such a top rank professional outfit as Celtic and will import the new-found expertise back home to Donegal.
He said that leaving Donegal to take up a full-time position with Celtic was never on the agenda, not least because despite winning the All-Ireland title for the first time in 20 years, there's still unfinished business in the county.
"We have created something within our own group of players that I feel is special. They have put everything in their lives into the side in terms of day-to-day stuff and put football at the centre. It would be wild hard to walk away from that," he said.
McGuinness is convinced that despite delivering the top two years in Donegal history, the best is yet to come from this group of players.
"I would feel that we're 60-65pc of what we can be. These boys are still learning. Even the All-Ireland final was a huge learning experience for them. They deviated from what we were talking about beforehand.
"Was that the pressure of the All-Ireland final? Was it the crowd? Was it the atmosphere? I don't know, but I do know that we were lucky enough to win the game and still get that experience which will hopefully stand to us if we get into that situation again."
It's most unusual for the manager of an All-Ireland-winning side to declare that his squad are only at two-thirds of their potential, but McGuinness is convinced that a big improvement is possible.
"They're young and they're learning. Even Michael (Murphy), the captain of the team, is only 23 years old and learning and growing all the time. There are eight or nine players like that."
The prospect that Donegal could still improve substantially is pretty worrying for the rest of the big contenders as they ease themselves back to training for the 2013 season. However, with McGuinness' bold claim of the latent potential awaiting release comes the honest acceptance that there's no guarantee it will fully emerge.
"It's there, provided you can find it. Do you know any teams that are operating at 100pc? There's 35pc more out there (for us), can we get 20pc of it? Can we retain the good work we did defensively and the good work we did offensively? There's no guarantee, but you have to work unbelievably hard to try and push the thing forward all the time."
McGuinness accepts that talk of an All-Ireland double is inevitable in Donegal, but said such thoughts are not even on his radar at this stage, just as ending the long wait for a visit from Sam Maguire wasn't mentioned at the start of this year.
"We set out to win the first game and hope that we could get traction. It will be the same again. For us, a huge focus will be on Tyrone in the first round of the Championship. If we don't win that game, it is a long, long road to the second competition.
"It's just about that game for us. That's the way it was this year for Cavan in the first round. It will be no different next year."
Actually, it will. Now, Donegal are All-Ireland champions and hoisted onto a pedestal where all-comers will be keen to have a shot at them.
"We'll have to cope with that, but these lads are good enough to do that," said McGuinness.