Michael Mole stopped 30 shots and the Grizzlies used defenseman Brett Beauchamp's first pro goal, a strike 3 minutes, 30 second into overtime, to earn a 3-2 lead at The E-Center.
Alaska leads the best-of-7 series 2-1 entering Game 4 at The E-Center.
The Aces won both Games 1 and 2 2-0.
Wednesday's game was another goaltending duel. Lamoureux, who posted back-to-back shutouts in the first two games of the series, stopped 40 shots.
The Aces jumped to a 1-0 lead eight minutes into the second period on the first playoff goal of winger Matt Stefanishion's career. Defenseman T.J. Fast, back with the Aces from Peoria of the American Hockey League, rushed the puck up the left wing and deep into Utah territory before centering to Stefanishion. With winger Cam Keith headed to the net to provide traffic, Stefanishion faked a forehand shot and flicked a backhander into an open net.
But the Grizzlies finally solved Lamoureux eight minutes later when Vladimir Nikiforov beat Lamoureux, who was screened by James Sixsmith, with a right-wing wrister off the rush to forge a 1-1 tie.
The goal marked the first Lamoureux had surrendered to the Grizzlies in 280 minutes, 27 seconds, the equivalent of four regulation-length games and two periods. Lamoureux had shut out the Grizzlies four straight times, two in the first two games of the series and two in the regular season.
The Aces regained the lead at 2-1 with eight minutes left when defenseman Matt Shasby started and ended a gorgeous play. Shasby rushed the puck up the left wing and centered to Colin Hemingway steaming down the slot. Hemingway immediately dish to his right to Cam Keith, who centered to Shasby at the left post, where he was left with an easy tap-in.
But Nikiforov struck exactly three minutes later, deflecting Mike Walsh's drive to give the Grizzlies a 2-2 tie.
The Aces enjoyed a glorious chance for another go-ahead goal in the waning minutes, but Mole dove to his left and flashed leather to rob Josh Soares with a glove save on the power play. The Aces killed a Grizzlies power play in the last two minutes of regulation after Shasby was whistled for high-sticking Tim Verbeek.
Through two periods, the Grizzlies outshot the Aces 29-16 and Alaska's frequent turnovers made for a busy night for Lamoureux, who time and again erased the mistakes of his teammates.
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