Michael McLeod scored in double-overtime as the Mississauga Steelheads edged the Peterborough Petes 2-1 to take a 3-0 lead in the eastern final.
McLeod scored his eighth of the post-season 10:29 into the second overtime period.
Spencer Watson tied the game for Mississauga early in the second period.
Steelheads goaltender Matthew Mancina made 28 saves. Peterborough's Dylan Wells stopped 53 shots in the losing effort.
Mississauga can close out the best-of-seven Eastern Conference final with a win in Game 4 on home ice tomorrow.