Dolphin blew a 14-point half-time as Cork Constitution finished strongly to win this rip-roaring Ulster Bank League derby clash at Musgrave Park.
Prop John Ryan emerged as the unlikely match winner, his try in deepest injury-time putting Constitution ahead and Johnny Holland's conversion wrapped up the result.
At that stage, Dolphin were down to 13 men after Danny Barnes saw yellow and prop Christy Condon followed him into the sin-bin for a high tackle.
Dolphin were chasing their fourth Division 1A victory on the trot. They were also looking to avenge an 18-13 reversal at Temple Hill earlier in the campaign.
Although Holland put fourth-placed Constitution ahead early on, the visitors were soon playing catch-up after losing number 8 James Ryan to the sin-bin.
Barry Keeshan slotted a levelling penalty and then the experienced out-half converted lock Chris Rowe's try to give Steve Ford's men a 10-3 buffer.
The Dolphin pack profited from a solid set piece, winning some of the visitors' lineout throws and busy flanker Miah Cronin nipped in for a converted try on the stroke of half-time.
That score gave the hosts a considerable boost and the vocal home crowd were willing Dolphin to push on in the second period.
However, derby games of this nature are notoriously tight affairs and Constitution remained in touch thanks to the boot of Holland.
The young out-half, with 109 league points to his name before kick-off, was holding his own against his opposite number Keeshan in terms of influencing play and converting from the kicking tee.
But Dolphin were within touching distance of the win following a smashing try from Munster's David O'Callaghan which began with a break out of the hosts' 22.
Keeshan converted for a 24-6 lead, only for O'Callaghan's Munster colleague Brian Hayes to snap a quick try back for Cork Con with Holland supplying the extras.
That kept Brian Walsh's charges in the hunt and although Dolphin defended in determined fashion as the clock ticked down, mistakes did creep into their game.
A missed kick to touch and the concession of a penalty for excessive use of the boot invited Cork Con forward, with Holland setting up a close-in lineout.
They worked it into a scrum and then replacement prop Bryan Cagney burrowed over for a converted try, which looked like being a consolation score.
But Dolphin blundered with an accidental offside, handing a late scrum to Constitution and in a cruel twist of fate the home side lost their grip on the game during a lengthy spell of injury-time.
The increasing penalties led to Barnes and Condon seeing yellow, and the visitors had enough time for Ryan to force his way over for the most important try of an entertaining contest.
Referee: Olly Hodges (IRFU)