Nemo dominated for long periods and commanded a seven-point lead with six minutes remaining but dropped their intensity for the finale.
There were many heroes for Blackrock, but Cathal Cormack’s goal deep into added time settled this intriguing encounter.
The opening 10 minutes saw both teams commit niggling fouls, but once the players settled and found their stride the huge attendance witnessed some outstanding hurling.
No doubt the pace of the Nemo forwards posed the Rockies numerous problems and two first-half goals from Conor Horgan and Shane Martin saw them deservedly lead 2-6 to 0-8 at the break.
The tempo increased on the restart and Nemo made two astute substitutions midway through the half when David Niblock and Stephen Cronin were introduced.
Niblock made an instant impact, scoring a classy goal with 10 minutes left and when Alan Cronin Snr followed up with a similar strike two minutes later the writing looked on the wall for Rockies.
But they were given a lease of life when a tame Colin O’Leary shot was fumbled by Nemo substitute keeper M A Martin and ended up in the net. Nemo failed to score again before a brace of points from David O’Shea and Brian O’Keeffe and Cormack’s magnificent late goal gave Blackrock an unlikely win.
Scorers for Blackrock: C Cormack (2-1), D O’Shea (0-6, 5fs), C O’Leary (1-2), B O’Keeffe (0-2), F Ryan (0-1).
Scores for Nemo Rangers: S Martin (1-3), C Horgan, D Niblock, A Cronin Snr (1-0 each), B Twomey, J Masters (1f) (0-2 each), S Horgan (0-1).
BLACKROCK: P Delaney; J Ryan, P McCarthy, R Laide; M O’Donoghue, W Sherlock, S Murphy; L Conway, A Murphy; C O’Leary, D O’Shea, C Cormack; B Cashman, F Ryan, B O’Keeffe.
Subs: C Crowe for B Cashman (ht), E Cantwell for P McCarthy (ht), M Russell for L Conway (36), A Nolan for C Crowe (50), F De Faoite for F Ryan (55).
NEMO RANGERS: E Greene; S Lyons, P Brophy, J Cowhig; E O’Sullivan, P Morgan, J Masters; S Horgan, B Twomey; S Cronin, A Cronin Jnr, A O’Donovan; S Martin, A Cronin Snr, W Morgan.
Subs: M A Martin for E Greene (inj 35), D Niblock for A O’Donovan (45), S Cronin for J Cowhig (48).
Referee: Dave Daly (Brian Dillons).