The lead didn't last long, as the game's first penalty led to a Vegas power play goal from Karlsson, a shot from the left dot for his second tally of the game.
The hat trick came with just under nine minutes left, a nifty backhander from just outside the crease that dove under the crossbar. Mark Stone made the great feed that set Karlsson up in that spot.
"Right from the start, it was a good hockey game," said Ducks coach Dallas Eakins. "There was lots of talk in the dressing room before. They were really engaged and it carried into the game. We could've made a choice when it went to 5-3. We could've chosen to get through it and start thinking about our next game, or we could choose to dig in and fight on. Good on the group for making the right choice."
A frenetic pace over the opening 13 minutes saw no stoppages in play until Patrick Brown punched in a loose puck from just outside the crease to make it 1-0 Vegas. It was the second career goal for Brown, who was just recalled by the Golden Knights for the first time today and hadn't played in the NHL since the 2016-17 season with Carolina.
Despite the back-and-forth, the Ducks had only one shot to Vegas' nine through the opening 15 minutes, and they looked poised to finish the first period scoreless. That was until Devin Shore deftly tipped through a shot from the point with just 0.6 seconds left on the clock to tie it 1-1.