O'Mahony scored eight points, including the last three of an enthralling contest in which the sides were level at 2-07 to 1-10 at half-time - Limerick goalkeeper Brian Murray netting a penalty with the last strike of the half.

Dublin got off to a whirlwind start with a first minute goal from teenage forward Liam Rushe.

A long range free bounced in front of Limerick net minder Murray, giving Rushe the chance to get the vital touch.

Alan McCrabbe scored eight points for Dublin whose lack of experience at this level told in the second half when they had a number of frustrating wides.

It took Limerick until the 60th minute to lead for the first time, and they pushed on right to the finish as they made it through to the All-Ireland's last-four for the second time in three years.

Justin McCarthy's men will meet Munster champions Tipperary in a semi-final clash at Croke Park on August 16.

Dublin had a dream start when Rushe goaled inside 30 seconds, nipping in on the end of a long range free from McCrabbe.

David Sweeney put over a superbly-taken point and when McCrabbe had a marvellous point from a sideline cut, Dublin led 1-03 to a 0-01 for Limerick, with O'Mahony their opening scorer.

Kilmallock clubman O'Mahony pointed a second free, which was countered by a glorious point by Liam Ryan for Dublin.

A third free by O’Mahony kept Limerick in touch but Dublin continued to dominate and David Treacy put over a sweetly-struck point to make it 1-05 to 0-03.

But a productive two-minute spell for Limerick saw Paudie McNamara make a great catch ahead of defender Tomas Brady and the Shannonsiders full-forward raced through to beat Gary Maguire for Limerick's opening goal.

Within a minute James Ryan had a point and the sides were level after 17 minutes with yet another O’Mahony free.

Dublin edged back in front with David O'Callaghan's point, which was quickly cancelled out by a free from Andrew O’Shaughnessy.

A terrific point from 65 yards by Michael Carton gave Dublin new confidence and goalkeeper Maguire made a marvellous save to deny the in-form McNamara.

McCrabbe and James Ryan exchanged points before McCrabbe and substitute Shane Durkin had Dublin three points clear again.

But just on the stroke of half-time, this end-to-end game took a dramatic turn.

As Paul Browne bore down on the Dublin goal, he was deemed to have been hauled down.

Limerick goalkeeper Murray raced forward to crack the resulting penalty past Maguire and make it 2-07 to 1-10 for the break.

Dublin started the second half in style and had two points inside three minutes from McCrabbe and team captain Stephen Hiney.

A point from the sideline from O'Mahony was followed by a superb score by the returning Ross O'Carroll and then James Ryan and McCrabbe swapped points.

O'Shaughnessy (free) and David O'Callaghan exchanged points as the tempo increased and both sides went hell for leather, playing their hearts out for the prize of a showpiece semi-final.

Limerick hit the front for the first time on the hour mark but fittingly it was man-of-the-match O'Mahony who turned the screw on Dublin with the last three points - a '65', a sideline cut and a free - to put an end to the gallant Championship run of Anthony Daly's young side.

Scorers: Limerick: G O'Mahony 0-08 (0-05f, 0-02sl, 0-01 '65'), A O’Shaughnessy 0-05 (0-05f), J Ryan 0-04, P McNamara 1-01, B Murray 1-00 (1-00pen).

Dublin: A McCrabbe 0-08 (0-07f, 0-01sl), L Rushe 1-00, D O’Callaghan 0-02, S Hiney, M Carton, R O'Carroll, L Ryan, D Sweeney, D Treacy, S Durkin 0-01 each

LIMERICK: B Murray; D Reale, S Lucey, M O’Riordan; G O’Mahony, B Geary, M Foley (capt); D O'Grady, S Hickey; J Ryan, D Breen, W McNamara; A O’Shaughnessy, P McNamara, .

Subs used: O Moran for W McNamara (31 mins).

DUBLIN: G Maguire; N Corcoran, T Brady, S Hiney (capt); M O’Brien, J Boland, M Carton; J McCaffrey, A McCrabbe; R O’Carroll, L Ryan, D Sweeney; D O’Callaghan, L Rushe, D Treacy.

Subs used: S Durkin for McCaffrey (28 mins), K Flynn for Ryan (49), P Carton for O'Carroll (55).

Referee: Michael Wadding( Laois)