Wearing number 22, which corresponded to Joseph Cooney in the match programme, the 2017 Hurler of the Year slipped into the action as a late substitute.

Within minutes he was involved in two huge moments; firstly being poleaxed by a shuddering John Hetherton charge which earned Dublin's top scorer a red card, then slotting over the stoppage-time winner from a sideline cut.

If anyone was in any doubt about the identity of the mystery Galway substitute - there are no official announcements made at Parnell Park - then it became clear once Canning stood over that sideline.

Displaying typical poise, he contorted his body in familiar fashion to cut the ball up into the air, sending it sailing over the bar on a left to right flight arc.

It was a timely intervention from one of the greats of the game because Galway had coughed up an eight-point lead and were in danger of a chastening loss.

Dublin never actually led in the game but had vital momentum when they restored parity after a 66th minute Sean Moran goal and back to back Oisin O'Rorke points.

Mattie Kenny's players couldn't finish the job though and it's Galway, courtesy of Canning, that advance to play Wexford in next weekend's Walsh Cup final.

Galway lined out with five of last August's All-Ireland final team in their lineup including Cathal Mannion who impressed with 10 points, five from frees.

They schooled Dublin in the first-half, picking off their points with the minimum of fuss and surging 0-15 to 0-8 at half-time with seven different players getting on the mark. Dublin, in contrast, managed just three points from play.

The hosts had the wind after the break and capitalised on it, falling eight points down but then outscoring Galway by 1-7 to 0-3 in the closing 20 minutes.

That's the sort of grit and determination that will please new manager Mattie Kenny who noted they might have stolen the win if Donal Burke's 47th minute flicked goal hadn't been ruled out for a controversial square ball call.

Galway will face Wexford in the final, after Davy Fitzgeralds men beat Kilkenny by 0-16 to 0-13.

Scorers for Galway: C. Mannion 0-10 (5 frees); B. Concannon (0-3, 1 free); S. Blehane, D. Glennon (0-2 each); P. Mannion, A. Harte, C. Whelan, J. Canning (1 s/l) (0-1 each).

Scorers for Dublin: J. Hetherton (0-8, 8 frees); S. Moran (1-0, pen); C. Crummey, E. Dillon, D. Burke, O. O'Rorke (2 frees) (0-2 each); F. Whitely (0-1).

Galway: J. Skehill; J. Grealish, J. Fitzpatrick, S. Linnane; K. Hussey, P. Mannion, A. Harte; S. Kilduff, C. Mannion; P. Brehony, C. Whelan, S. Blehane; T. Monaghan, B. Concannon, D. Glennon.

Subs: S. Loftus for Kilduff 56, S. Maloney for Brehony 56, R. O'Meara for Glennon 62, J. Canning for Blehane 67.

Dublin: A. Nolan; P. Smith, E. O'Donnell, L. Gannon; C. Crummey, S. Moran, S. Barrett; R. McBride, T. Connolly; J. Hetherton, F. Whitely, F. McGibb; E. Dillon, L. Rushe, D. Burke.

Subs: S. Treacy for Smith h/t, D. Gray for O'Donnell 47, C. Conway for McBride 48, O. O'Rorke for McGibb 51, D. Keogh for Barrett 62, D. O'Connell for Whitely 64, C. Burke for D Burke 70.

Ref: P O'Dwyer (Carlow).