The champions looked set to bow out in a repeat of last year’s final, trailing by a goal with two minutes left against arch-rivals Loughrea. But Ronan O’Meara flicked home a goal to level the match and Canning, scorer of 1-10, landed the matchwinner in front of a crowd of about 6,000.
Johnny Maher, who had led the Loughrea challenge, had a last-gasp chance to level the match but his free from the right tailed wide and Portumna held on to win, 2-15 to 1-17.
The match between two sides who have produced fireworks over the past decade was sporting throughout but there was an outbreak of violence on the sideline between some officials from both sides after the full-time whistle.
Portumna led 1-9 to 0-9 at the break after a sideline from distance by Joe Canning ended up in the net, with older brother Ollie causing havoc in front of the posts. Johnny Maher hit an excellent goal to inspire Loughrea but another soft goal cost them dearly.
Portumna face Craughwell in the semi-final after they disposed of Tommy Larkins by 0-19 to 1-13 in the quarter-final at Loughrea yesterday.
Craughwell, who won the last of their five titles in 1931, led 0-7 to 0-5 at the break and with Keelan Cullinane in form, always held an edge.
Tommie Larkins hit the front with a Jason Flynn goal but Craughwell got on top again to close out the game.
Gort, who won their sixth title in 2011, marched into the last four with an impressive 3-11 to 0-11 win over a Killimordaly side who lacked power up front despite a good showing from Brian Burke.
Former All-Ireland minor winning captain Richie Cummins was the hero for Gort at full-forward, hitting 2-2.
Gerry Quinn had their first goal from a penalty to lead 1-7 to 0-6 at the break and Cummins fired his goal within a minute of the restart.
Ardrahan and Turloughmore must meet again after drawing 0-18 to 1-15 on Saturday. The sides went in level at 1-6 to 0-9 but Turloughmore opened up a five points lead in the final quarter. Ardrahan rallied with efforts from county stars Jonathan Glynn and Iarla Tannian before Callinan levelled at the death.
Meanwhile Anthony Cunningham will beef up his Galway management team with former All-Star Pat Malone coming on board as a selector. Cunningham, who will tonight be reappointed as Galway manager, brought his former teammate on board to join selectors Eugene Cloonan and Damien Curley.