Keller made it 2-0 on the power play at 11:57 of the second period, taking a through-the-legs pass by Cooley from the slot, and snapping it short side past Levi’s glove.
Draisaitl cut the lead to 2-1 at 13:54, on a give-and-go from Connor McDavid that he slid through Vejmelka’s legs.
The assist extended McDavid’s season-long point streak to all seven games (four goals, 14 assists).
“It was a tight-checking game, both teams really dug in,” McDavid said. “I thought it was a great game all around. Two good teams that were working and checking and it came down to special teams, they found a way to get a couple and we didn’t.
“We expect to win every night no matter who is in the lineup. It’s just the way it is.”
The Mammoth went ahead 3-1 just 23 seconds later at 14:17, when Cooley drove to the crease to reach a backhand pass from Vincent Trocheck, and lift it past Levi’s glove.
“I think he said it, but it almost does feel like it’s summertime and we’re just out there playing around. Obviously, a great pass by him and hopefully we’ll keep it rolling,” Cooley said. “Obviously, they’re an unbelievable team over there. Some of the best players in the world, and when we have a showing like that, playing committed hockey, we can beat anyone in this league.
“I think that’s the confidence we need and the confidence we’re going to have going into the rest of the season.”