The forward skated from the right wing boards behind the net, lifted the puck onto his stick and stuffed it past the right shoulder of goalie Sam Montembeault.
"I looked to see if I could make a play to somebody in the slot, and once I realized that I had a little bit of space I figured I'd just try it," Zegras said. "So, I don't know, kind of lucky."
Troy Terry had a goal and two assists, Cam Fowler had a goal and an assist, and Anthony Stolarz made 36 saves for Anaheim (22-16-8).
Zegras' highlight goal gave the Ducks a 4-1 lead 1:25 into the second period.
"If you're a fan and you're sitting from afar, you're probably thinking, 'Oh, this is the greatest thing,'" Ducks assistant coach Mike Stothers said. "And as you probably saw the reaction from our team and on the bench when [Zegras] scored that goal, the lacrosse goal, it was one of shock, amazement, and then there were some like myself that showed no expression whatsoever because you know what? There's a game to be played and we need to continue to play it the right way.
"We let Montreal back into the game. You always worry about things like that. There's a right way to bring it home and we're still working on that."