Facing a three-goal deficit twice against St. Thomas Academy did not faze Duluth East. Lately, it’s been the Greyhounds’ formula for success.

A stirring rally, featuring a trio of third-period goals, sent the game to overtime.

“When we tied it we said, ‘We’ll play all day,’ ” Duluth East coach Mike Randolph said. “I’ve never seen them get tired. They don’t quit.”

The Greyhounds advanced with a 6-5 upset as Ryan Peterson tipped in the game-winner just one minute, 31 seconds into the extra session.

Senior forward Peter Tufto scored twice and assisted on three other goals as No. 3 seed St. Thomas Academy (24-5) fashioned a 5-2 lead through two periods.

But Duluth East, which fought back from a 3-0 deficit against Elk River/Zimmerman to win the Section 7 championship, kept coming. Peterson’s first goal, scored at 2:34 of the third period, sparked hope.

“I thought we had the momentum after that one,” Peterson said. “That got us going. They didn’t get any goals and we kept on going.”

“On the bench, after every goal we said, ‘Keep believing, keep believing,’ ” Greyhounds senior co-captain Brian Bunten said.

Goals from Evan Little and Nick Funk in the last three minutes of regulation put Duluth East (15-10-4) in control. Little’s power-play goal was especially deflating.

“It was tough when the buried that power-play goal,” Cadets’ senior Christiano Versich said. “You could just see they had that extra step. They thought they could come back and win.”

Duluth East rallied from a three-goal deficit to force overtime and defeat St. Thomas Academy 6-5 in Thursday’s second Class 2A quarterfinal at Xcel Energy Center.

Ryan Peterson tipped in the game-winner.

Senior forward Peter Tufto scored twice and assisted on the Cadets’ three other goals as No. 3 seed St. Thomas Academy jumped to 5-2 lead in the second period.

But Duluth East, which fought back from a 3-0 deficit against Elk River/Zimmerman to win the Section 7 championship, showed similar moxie against the Cadets. Trailing 3-0 in the first period, the Greyhounds rallied for a pair of goals.

Behind 5-2 after two period, Duluth East stirred its group of red-clad fans with a trio of third-period goals to force overtime.

The Greyhounds advance to play No. 2 Edina in Friday’s semifinal.