Jonathan Huberdeau scored 17:45 into overtime as the Saint John Sea Dogs defeated the Owen Sound Attack 3-2 at the MasterCard Memorial Cup on Monday.
Huberdeau was left all alone in the slot, and he fired a wrist shot into the top corner of the Attack net past goaltender Jordan Binnington.
The Sea Dogs advanced to Sunday's final with the win.
Tomas Jurco tied the game with 3:27 left in the third, as the Sea Dogs overcame a 2-0 first period deficit to set up the comeback win in a wild, back-and-forth overtime.
Stanislav Galiev had Saint John's first goal, and goaltender Jacob DeSerres made 47 saves to earn the win.
Matt Petgrave and Andrew Shaw replied for Owen Sound. Binnington made 41 saves in a losing cause in net in front of a largely pro-Attack capacity crowd at the Hershey Centre in Mississauga.
The Sea Dogs are now 2-0-0 after opening the tournament Friday with a 4-3 win over the host Mississauga St. Michael's Majors.
Owen Sound, which beat the WHL's Kootenay Ice 5-0 on Saturday, fell to 1-1-0.
Petgrave opened the scoring for Owen Sound on a fluke goal at 6:36. The Brampton, Ont., native picked up a clearing attempt at the left point and fired a weak shot toward the net that was tipped past DeSerres by Sea Dogs defenceman Gabriel Bourret.
Then with Bourret off for hooking, Mike Hamlo's shot from the right point was deflected past DeSerres by Shaw to give Owen Sound a 2-0 lead heading into the first intermission.
The Attack would have had a 3-0 lead if not for a diving glove save by Toronto native DeSerres on Cameron Brace at the edge of the crease with just 11.1 seconds remaining in the period.
Owen Sound dominated the first half of regulation play. Led by six-foot-three, 206-pound captain Garrett Wilson the Attack dished out hard hits to slow down a high-powered Sea Dogs offence that scored 324 goals during the QMJHL regular season.
But Saint John began taking over the game, generating most of the scoring chances in the second and third periods.
The Sea Dogs cut the lead in half on the power play at 13:39 of the second. Jurco picked up the puck behind the Attack goal, took it to the corner then spun around and fired a cross-ice pass through the crease to Galiev who tipped it into the open goal.
Jurco then tied the game late in the third when he picked up a point shot wide off the boards and roofed it over Binnington to send the game into overtime.
Owen Sound went 1 for 7 on the power play. Saint John was 1 for 6.
Saint John takes on the Kootenay Tuesday to wrap up its round-robin play.
Owen Sound wraps up the round-robin on Wednesday when it takes on the Majors, who it beat four games to three to capture the OHL championship.