REGINA — The Seattle Thunderbirds knocked off the top-ranked team in the Canadian Hockey League to advance to the Memorial Cup.

Alexander True scored the winner 12:36 into overtime as Seattle edged the Regina Pats 4-3 on Sunday, winning their best-of-seven Western Hockey League final in six games.

True's goal capped a Thunderbirds rally that saw them score three unanswered goals to erase a 3-1 deficit.

Sami Moilanen, Ryan Gropp and Keegan Kolesar, with the tying goal 17:06 into the third period, also scored for Seattle.

Sam Steel, Josh Mahura and Austin Wagner supplied the offence for the Pats.

Thunderbirds goaltender Carl Stankowski made 28 saves. Regina's Tyler Brown stopped 39 shots.

Seattle joins the Ontario Hockey League champion Erie Otters, the Quebec Major Junior Hockey League champion Saint John Sea Dogs, and the host Windsor Spitfires in the Memorial Cup, which begins Friday.