Moments after Mahtomedi's apparent game-winning goal was ruled to have come after time expired, Hermantown's Jared Thomas scored 1:14 into overtime to give the Hawks a 7-6 win in the Class 1A semifinal Friday at Xcel Energy Center.
Hermantown will face either defending Class 1A champion Breck in Saturday's championship game, after Breck beat Warroad 4-2.
The Hermantown-Mahtomedi semifinal was stressful for both teams.
"Nerve wracking," said Hermantown coach Bruce Plante. "Just gotta keep playing."
"I think we all threw up on that roller coaster," said Mahtomedi coach Jeff Poeschl.
At the end of regulation, Mahtomedi players thought they had won after Charlie Adams ripped a shot past Hermantown goaltender Tyler Ampe with the game clock at zero. Mahtomedi players were jubilant, throwing their equipment in the air and celebrating on the ice.
A video review clearly showed the puck failed to cross the goal line before time expired, and the game would go into overtime.
"To be that close, we thought we had it," said Adams through tears. "It hurts."
Hermantown went into the extra period refreshed after the short wait for the video replay, while Mahtomedi was spent from its premature celebration.
"They called no goal and we got our legs back," said Thomas, a sophomore who rushed the net and slid the puck past a sprawling Brad Wohlers, sending the Hawks and their supporters into a frenzy.
The furious ending capped a wild three periods in which the teams traded goals until Brandon Zurn's score gave the Zephyrs a 6-4 lead. But Hermantown's Charlie Comnick, who had scored earlier in the third, got two more goals in a little over a minute to tie the score.
Zurn and Hermantown teammate Jared Kolquist both scored twice in the game, while Adams scored twice for Mahtomedi. In a matchup between two Mr. Hockey candidates, Mahtomedi's Ben Marshall had a goal and two assists, while Hermantown's Adam Krause was kept off the scoreboard.
Hermantown goes for its second state championship on Saturday, having won the 1A title in 2007.
Mahtomedi has never made it to the boy's hockey state final in seven appearances in the state tournament.