Makar scored on the power play to make it 1-0 when he beat Rittich with a shot from the point at 2:01 of the first period.
"Obviously, [playoffs are] right there in front of us. We have to be ready and we've been on a little bit of a not-so-hot streak here, but at the same time I still think the confidence in the group is very high and we know what we're capable of," Makar said. "Obviously, we got one more coming up here, but we've definitely been ready for playoffs for the past few weeks, that's for sure."
Lehkonen pushed the lead to 2-0 after he redirected Josh Manson's shot at 6:46 of the period.
Duchene scored to make it 2-1 with a wrist shot from the point that went through traffic and Kuemper at 11:46 of the first.
"To us it's important, we felt, coming into these few games as we want to still play at a level that that's going to give us the best chance to win and be consistent in that," Predators coach John Hynes said. "So when you do start playoffs, regardless of who you play, that you feel good about your game and feel like your game's in order and guys are playing the way that we need to be able to play."
O'Connor extended the lead to 3-1 when he fired a loose puck into the open net while both teams thought it had gone out of play at 16:59 of the period.
"It just sort of landed right where I shot it off Josi," O'Connor said. "I think it landed right on my stick pretty much, and everyone was looking around. So fortuitous bounce for sure, but it was nice to get a greasy one there."