Josh Currier scored four goals, while Graeme Hossack and Cody Jamieson added two each for Rochester, which won its 15th straight home playoff game to extend a league record.
Jeff Shattler scored three goals and Ryan Keenan added two for Saskatchewan, which is looking for its second championship in three years. Evan Kirk made 39 saves for the Rush.
The best-of-three series will be decided next Saturday in Saskatoon, just the second time in the five-year history of the three-game format that a decisive third game will be needed.
Saskatchewan scored on two of its first three shots to take an early lead. Defence then prevailed on both sides before Currier scored midway through the first quarter. The Knighthawks then scored twice in a 1:06 span late in the frame before Keenan tallied with 3.2 seconds remaining to tie the game at 3-3.
Austin Shanks gave Rochester a 4-3 lead with a short-handed goal 26 seconds into the second quarter, and Currier gave the Knighthawks a two-goal cushion at the 5:08 mark after cutting across from the left side and sneaking a shot past Kirk.
(The Canadian Press)