Joe Canning struck a stoppage-time equaliser to give Galway a 2-13 to 0-19 draw with champions Kilkenny and send the All-Ireland SHC final to a replay for the first time since 1959.
Canning produced a piece of magic with a superb 10th minute goal, and his accuracy from placed balls helped the Tribesmen to a 1-4 to 0-2 lead ahead after 20 minutes.
Niall Burke rose high to collect and finish with a point, and while Kilkenny pulled back a point through TJ Reid, Galway continued to perform with confidence, and when wing back Niall Donoghue finished off a composed passage of possession play with a long range point, they led by 1-7 to 0-3.
Kilkenny staged a late flourish, with Shefflin nailing three frees, a welcome respite that reduced the deficit to five, Galway ahead by 1-9 to 0-7 at the break.
Kilkenny's Aidan Fogarty darted through to narrow the gap to a single point in the 49th minute, and it was Shefflin who brought the Cats level with his first point from play, before adding the lead point from a monster free.
Galway had managed just a point in the previous 20 minutes, but they struck a major blow when Niall Burke picked up a loose ball and set off towards goal with intent and blasted a fierce shot past David Herity in the 55th minute.
Two Canning frees kept Galway hopes very much alive, but Shefflin was the man who was destined to decide this gripping decider.
When Kilkenny were awarded a penalty for a foul on Larkin, King Henry opted to tap the ball over the bar, but Canning held his nerve to level it in stoppage time from a free.