All-Ireland SFC semi-final: Declarations of championship intent are easily made but their substance is never truly tested until the white-hot afternoons of late summer. Mayo came to Croke Park yesterday and having played second-gear football all championship, they took off their gloves, slapped Dublin's face with them and demanded a duel.

What followed was a monumental game of football, a match to be filed along with the very best of the past couple of decades. The pace and physicality were redolent of wild horses busted free of a coral. The plot switched and jagged like a great thriller. The soundtrack was a cacophony of bellowed passion. The ending was as surprising as it was fitting. Mayo won a great game of football.

In the end there was a point separating the teams, a hair's breadth in terms of the scoring. Between them in terms of knowing how to win a tight game, there was, surprisingly, more of a gulf. Dublin haven't progressed in this regard since the semi-final of 2002. Mayo have learned something from the litany of bitter defeats they have endured at Croke Park. Yesterday they stood up.

When they were seven points down in the second half with Ronan McGarrity sitting concussed in the stand, when the time came for Mayo to grasp the old fig leaf of teams who "put up a good show but . . ." what did they do? They stood up.

Ah, Mayo. How often have we seen them wilt on days like these? How often have they offered 20, maybe 25 minutes of sprightly football only to droop and fall away? They showed their teeth early yesterday, bursting out of the tunnel, posing for their photo and then opting to warm up at the Hill 16 end, where Dublin hold the long-term lease.

Some chaos ensued. Mentors of both teams bumped each other like dodgems. Players tangled. A dietician got hit with a ball and was knocked unconscious. At the time we viewed Mayo's incursion in the dim light of the hundred disappointments they have offered us in the past. Forgive us, but it is 55 years since their last All-Ireland. We muttered to ourselves that they were playing silly buggers. By tea-time, though, we were admiring their great big, clanking, steel cojones.

"We sat down for the photo and said for the hell of it, we'd go down," said team captain David Heaney afterwards. "We were just saying 'we're not afraid of ye. We'll stand up'.

"Analysts in the media were saying we'd go up, we'd play well, then we'd die. We just wanted to say we're here to win and that's that."

Here to win! Even when Mayo scored the first four points of the game we doubted that. History clouded our vision. Mayo had more generous leads at various stages of both instalments of the 1996 All-Ireland final. If ever a team knew how to find a way to lose, it was Mayo.

We ignored the other indicators. Mayo were coming out of the midfield commerce with a profit. They were varying the play well. Ciarán McDonald was labouring rather than orchestrating. The Mayo defence were throwing themselves on Dublin attackers like a great fire blanket.

Dublin, playing into the Hill end, were having trouble with the ignition but still we were blinded by preconceived ideas. Conor Mortimer missed a goal chance on four minutes when put through by Alan Dillon, the most illustrious of the worker bees in the Mayo forward lines.

Dublin had a series of chances with frees early on which suggested it might not be their day. Tomás Quinn hit the post with a 45 and followed up with two misses, one of which he will remember ruefully. He found his kicking later in the game and Dublin will wonder for a long time if Quinn, who has kicked them out of so many tight corners, might have saved them in the dying minutes when two dead-ball chances went abegging.

Dublin pulled back. A prosaic goal from Conal Keaney made it level and the teams were nipping and tucking for a little while until Quinn nailed a 45 with two minutes of the half remaining. It restored a one-point lead to Dublin but seemed more emphatic than that as it came as the climax of a little period when Dublin had two fine goal chances. One, from Jason Sherlock, was hammered back off the bar; the other, from Alan Brogan, came back off Aidan Higgins's face.

Mayo couldn't let it be till half-time, even. Two furious points from Kevin O'Neill and Conor Mortimer finished out the half and sent them to the tea-break believing.

We were half beginning to share their belief till Dublin came out for the second half and scored a goal and four points in the first five minutes. Rat-a-tat-tat. After 10 minutes they were seven points ahead having been a point down when they were coming back out.

They say the sign of a great poem is it is impossible to remove a single word without diminishing it. As such, this classic game probably deserves to be spared the pathologist's knife. No one act shifted the outcome. No one act was irrelevant to the outcome. When Dublin were seven points up, though, they were naked and at their most vulnerable.

Mayo got their subs on quickly. Two in the first half. Three before the 45th minute. Every one of them worked a treat. Andy Moran was the last in - 45th minute for James Nallen. Seven in it. Fool's errand.

"Andy Moran is a sub," said Mickey Moran afterwards, "usually a half forward. And we were putting him in for James Nallen. He turns and he says, 'I will get you a goal'. That's what he said. 'I will get you a goal'."

He did. Fiftieth minute. McDonald to Ger Brady, who plays a lovely pass to Moran, who finds himself with Shane Ryan and Stephen Cluxton still to beat. Dublin have taken off their full back by now and Ryan looks uneasy finding himself at the edge of his own square instead of doing the fine linking job he had been doing. Moran squirms, turns and dribbles a shot into the corner. Now we believed.

The rest is a dream of noise and excitement. One of those days. Moran said afterwards it was the first time in his football career he could remember feeling his heart beating in his chest. It was a sensation he shared with 82, 148 paying customers.

Dublin flatlined and didn't score for 21 minutes, having gone seven ahead. Mayo were level within nine of those minutes and when Brogan clipped a point with four left on the clock we thought a draw was the only straw for Dublin to clutch at. Not to be.

The winning point came from the bespoke boot of the most criticised player in Mayo, McDonald cutting in from the left and curling a sweet score into the Hill end, raising his finger and smiling broadly.

There were three minutes of what passes for ordinary time and three minutes of injury-time left but it seemed like the final nail.

Mayo ride on, tilting heroically at the windmill. Dublin go home to square one.

As for the dream final, Kerry versus Dublin? We will never know. Unheard melodies are never sweet.