Sometimes the fading of champions and arrival of new contenders happens as one seamless event without fanfare. Other times the occasion has more resonance and it's hard to avoid the conclusion that yesterday's Guinness All-Ireland hurling semi-final was one of these occasions.

On an unco-operatively wet and windy afternoon, the hurlers of Cork and Offaly staged a magnificent match at Croke Park. A late burst of scoring saw the young Munster champions topple the All-Ireland holders after a match which ebbed and flowed inscrutably until the closing minutes.

It was a conclusion which demanded a lot of Jimmy BarryMurphy's inexperienced charges, but they showed tremendous appetite for the endgame despite having looked like they were losing their nerve going into the final 10 minutes.

Throughout the team there were influential performers: from Donal Og Cusack in goal - who showed icy calm in the frantic closing minutes, taking dropping ball and wriggling out of the stampeding forwards in his goalmouth - all the way up to the livewires on the full-forward line.

Offaly went out like champions. At times, they hurled brilliantly and throughout the match met Cork's challenge head-on. Brian Whelahan had a majestic game in a defence which for long periods of the afternoon wrung the life out of the Cork attack.

Nearly half of the winning total, nine points, came in two distinct sequences - the five minutes after half-time and the eight minutes before the end. Offaly were unhappy at dozing off after the interval, but pressure had been building on them before the final damburst.

In the battle between the attacks, Cork's proved more penetrative. They were a bit more frenetic than the more experienced All-Ireland champions' forwards, but they created more chances even though their finishing was less precise and left them with twice as many wides.

At centrefield the champions had the better of exchanges with Cork's new pairing failing to emulate the performances against Clare and Waterford - although options in this area had been limited by the midweek injury to Pat Ryan who might have made an appearance had he been available.

Mickey O'Connell was out-of-sorts, but Mark Landers played well in the first half and came good again for the critical closing phase. Both of their opponents were in good form. Johnny Dooley gave a masterclass in economy of striking and hit two lovely points from play in the first half.

As ever, Johnny Pilkington kept pressing until the end and was moved up into the attack to try and rescue the momentum which was draining from them - as he had so spectacularly done against Clare in last year's drawn semi-final. He nearly succeeded, setting up Paudie Mulhare for a goal chance which was kicked narrowly wide.

But it was the performance of the two defences which dominated proceedings. If Whelahan was supreme at one end - although his brother Simon also gave another brilliant display - Brian Corcoran was imperious at the other. At times it recalled the National League quarter-final of four years ago when the two reduced that match to a private puck-around.

Cork's centre-back - the only survivor of their most recent All-Ireland final seven years ago - led his defence superbly. Occasionally he was discomfited by the rapier stickmanship of John Troy who, having moved back to the 40 from full forward, robbed Corcoran in mid-stroke and coolly hit the point which triggered Offaly's second-half comeback. But overall his was an immense contribution.

The steadiness of Cork's defence has sometimes been obscured by the box-office appeal of the forwards, but it has been the foundation of the team's achievements this year. Behind Corcoran, Diarmuid O'Sullivan gave another of those elemental displays which have marked his graduation to the full-back spot this year.

His physique gives him an obvious command, but he uses the advantage so well in attacking ball and his clearances are prodigious. Being marked by him must be like having a pteradactyl hovering in the background and Offaly tried three men on him without success.

This was an enthralling match because for the whole 70 minutes the result hung in the balance as phases of superiority came and went and each side looked at various stages to have given themselves a distinct edge.

The quality of Offaly's hurling in the first half was exceptional. Cork matched them for the first quarter, but were very much on the back foot as the half progressed. More worryingly, they were incapable of making any decent inroads on Offaly's lead. Three times in five minutes, the Munster champions equalised only to concede at the other end within a minute.

After 23 minutes the lead had stretched to three, 0-9 to 0-6. The ninth point was a precis of Offaly's acumen at this stage. Under fierce pressure from Sean O hAilpin, Johnny Dooley snapped up the ball, offloaded to Brian Whelahan whose dropping shot was scrambled clear only for the waiting Troy to clip over the score.

A 10-minute hiatus followed on the scoreboard, however, and it became apparent that Offaly, playing with the wind, were running the risk of taking an unrepresentatively small lead in at half-time. Cork's defence was coping well, with John Browne particularly alert in the left corner.

Yet, even the least optimistic Cork supporters in the crowd must have felt happy with an interval deficit of one point, 0-9 to 0-10. It arose largely because of Dickie Murphy's decision to play over three minutes of injury-time.

After Deane and Johnny Dooley had swapped frees, Deane managed to convert two more in this added-on period to bring the margin down to the minimum. Cork had also shown some promise, as well as keeping the score within reach.

Seanie McGrath and Deane were in slippery form. McGrath's pace gave Martin Hanamy some terrible problems before the veteran corner back was switched with Simon Whelahan. Neither of the Cork duo was particularly well-served by some very high deliveries into them and McGrath's facility even in these circumstances was impressive.

Fergal McCormack had won some ball early on from Hubert Rigney, who along with Kevin Martin played through the match after the fortnight-long injury scare involving the two of them, but in general the Offaly half backs were in unyielding humour.

The first of the two scoring salvos which effectively turned the match came after half-time. Four unanswered points tilted proceedings Cork's way. And they were phenomenal scores.

After O'Connell had hoisted over the opening shot in the 38th minute, the following three points were all the products of wonderful, direct hurling - two clearances from Corcoran transformed into points by McGrath and Ben O'Connor and a Cusack puck-out seized by Alan Browne and dispatched over the bar.

For whatever reason Cork lost momentum at this stage and managed only one point in the next 20 minutes. Offaly needed no second invitation and inexorably reeled in the lead and moved two points ahead.

There was panic in Cork's play. Deane began to miss frees and a sense of nervousness pervaded their play. At times they played into Offaly's hands by dropping high ball in on top of Kevin Kinahan, but at least they were creating chances.

In the 63rd minute, Kevin Murray claimed the first point of the winning move. A much-disputed free against Troy for handling on the ground presented Dean with the equaliser.

Their momentum restored, Cork broke the back of the champions with further scores from O'Connor, McCormack and Deane. McGrath nearly blazed a breaking ball back into the net after a Corcoran clearance.

There were alarums and excursions at the other end, but when the smoke cleared the result was clear and Cork's renaissance now moves to the last day of the season and a showdown with either Clare of Kilkenny.