Zellweger finished off a 3-on-2 break after Terry tied it 2-2 on a rebound of Cutter Gauthier’s shot off the post with Lukas Dostal pulled for the extra skater.
Jackson LaCombe also scored, and Dostal made 16 saves for the Ducks (12-6-1), who had lost three in a row (0-3-0) following a seven-game winning streak.
Dylan Guenther and Logan Cooley scored, and Karel Vejmelka made 23 saves for the Mammoth (10-7-2), who have lost five of six (1-3-2).
Cooley gave Utah a 2-1 lead at 9:19 of the third period on a one-timer from the right circle. He made a diagonal pass from the corner of the Anaheim zone to Mikhail Sergachev at the left point, and Sergachev took a few strides toward the middle of the ice before passing the puck back to Cooley for the goal.
The Mammoth did not get a shot on goal until Nate Schmidt's at 11:59 of the first period, which came with six seconds left on a power play.
LaCombe gave Anaheim a 1-0 lead at 15:52 of the first off a feed from Ryan Strome, a one-timer from the slot for his first goal of the season.
Guenther tied it 1-1 at 18:14 of the second on a one-timer from the left circle. Schmidt skated with the puck from the right point to the right circle trying to shake off Anaheim forward Ross Johnston before finding room to make a cross-ice pass to Guenther, who scored for the second straight game.
