Karel Vejmelka stopped Jack Eichel's initial chance at the edge of the crease, but as Ian Cole came in to swat away the rebound, he accidentally knocked away Vejmelka's stick as well. Eichel then regained possession of the puck below the goal line, and as Vejmelka was scrambling back into position, he passed out to the high slot, where Theodore buried a one-timer into an open net.
The best-of-7 series is tied 2-2. Game 5 will be at T-Mobile Arena in Las Vegas on Wednesday (10:00 p.m. ET; HBO MAX, Utah16, SCRIPPS, truTV, TNT, TVAS).
Brett Howden scored twice, and Eichel and Noah Hanifin each had two assists for the Golden Knights, who are the No. 1 seed from the Pacific Division. Carter Hart made 27 saves.
Nick Schmaltz had a goal and an assist, and Mikhail Sergachev had three assists for the Mammoth, who are the first wild card from the Western Conference. Vejmelka made 29 saves.
Pavel Dorofeyev opened the scoring at 1:12 of the first period. Ivan Barbashev fanned on a one-timer from the left circle, but the puck slid right to Dorofeyev, who finished past the outstretched left pad of Vejmelka to give the Golden Knights a 1-0 lead.
Howden made it 2-0 with a short-handed goal at 18:38. Mitch Marner intercepted the puck from JJ Peterka along the boards and sent a centering pass to Howden, who pulled the puck from his backhand to his forehand and deked around Vejmelka at the edge of the crease.
Cole Smith extended the lead to 3-0 at 3:26 of the second period, tipping in a shot from the left point by Hanifin.
Schmaltz began Utah's comeback at 8:04. Following an extended shift in the offensive zone, he chipped in the rebound of Lawson Crouse's shot past the blocker of Hart at the left post to make it 3-1.
Cole cut it to 3-2 at 8:33, scoring with a slap shot past the glove of a screened Hart from above the left circle.
Michael Carcone tied it 3-3 at 1:45 of the third period with a one-timer from the right circle that went short side under the glove of Hart.
Clayton Keller then gave the Mammoth a 4-3 lead at 5:10. His backdoor pass for Sergachev at the left post deflected off the body of a prone Theodore and trickled under Hart's left skate.
Howden tied it 4-4 with his second goal of the game at 10:25, redirecting Hanifin's shot from the left point.
Dorofeyev appeared to win it for Vegas at 10:22 of overtime on a rebound in the crease, but the call was reversed after a video review determined that Eichel was offside prior to the goal.
