Hertl redirected Jack Eichel’s shot on the power play. The goal came after William Karlsson tied it 3-3 at 16:23 with his second straight goal after Vegas trailed 3-0 entering the third period.
Ivan Barbashev scored, and Adin Hill made 21 saves for the Golden Knights (44-28-8), who won their second in a row and pulled to within one point of the Los Angeles Kings for third place in the Pacific Division.
Cale Makar had a goal and an assist, and Ross Colton and Mikko Rantanen scored for the Avalanche (49-25-7), who have lost four of their past five. Alexandar Georgiev made 26 saves.
Colorado pulled to within one point of the Winnipeg Jets for second place in the Central Division.
Barbashev cut it to 3-1 at 2:56 of the third period, putting the puck past Georgiev’s left pad after a wraparound.
Karlsson made it 3-2 at 6:35 with a power-play goal before tying it 3-3 with 3:37 remaining.
Colton gave the Avalanche a 1-0 lead at 7:26 of the first period when his shot trickled past Hill.
Makar extended it to 2-0 at 10:34 with a wrist shot over Hill’s glove.
Rantanen pushed it to 3-0 at 12:50 of the second period, backhanding a Josh Manson pass.
