Nick Schmaltz and John Marino also scored, and Karel Vejmelka made 31 saves for the Mammoth (14-12-3), who have won two in a row after losing the previous four.
Arshdeep Bains scored and Kevin Lankinen made 14 saves for the Canucks (10-15-3), who are winless in four games (0-3-1) and have one win in their past eight (1-6-1).
Sergachev put the Mammoth ahead 1-0 on the game’s first power play at 16:00 of the first period when his point shot deflected twice – first off Canucks forward Elias Pettersson, then defenseman Marcus Pettersson – and caught Lankinen sliding the other way.
Vejmelka made a couple great pad saves early, going left to right to deny Elias Pettersson in tight at 4:52, then the other way to rob Linus Karlsson on a backdoor chance at 5:08. He made another great pad save off Quinn Hughes on a 3-on-2 at 1:48 of the second period.
Vancouver controlled play for most of the second period but Schmaltz got through and deflected a Sergachev point shot down over the right pad of Lankinen from the slot at 14:05 to make it 2-0.
Bains pulled the Canucks to 2-1 on a rush chance 4:17 into the third period, driving to the net and deflecting Aatu Raty’s high shot from the top of the left circle past Vejmelka’s glove from close range for his first goal of the season in his 23rd game.
Daniil But, playing his second NHL game, appeared to make it 3-1 at 13:44 of the third period with Lankinen caught behind the net, but it was waved off because Utah forward Dylan Guenther made incidental contact with the Canucks goalie after he played the puck.
Stenlund made it 3-1 at 17:52, finishing a 3-on-2 rush by taking the puck to the net alone and deking around Lankinen on the backhand.
Marino scored short-handed into an empty net from his own end at 19:24 for the 4-1 final.
