Curtis Lazar scored his first goal of the season, and Akira Schmid made 31 saves for the Devils (6-3-1), who had won three straight, including a 5-3 victory at the Minnesota Wild on Thursday.
"We can't be winning games 5-4, 5-3," New Jersey defenseman Kevin Bahl said. "We've got to win them 2-1, 1-0 now. We've just got to be better all around."
Devils center Jack Hughes, who leads the NHL with 20 points (five goals, 15 assists) in 10 games, left the game with an upper-body injury at 9:56 of the first period. He lost his balance and crashed into the end boards after splitting a pair of St. Louis defenseman and releasing a shot on goal. Hughes briefly returned to the ice for a New Jersey power play that began at 10:50, but soon left for good.
"He'll just be evaluated tomorrow," Devils coach Lindy Ruff said. "We'll see where we're at."
Losing Hughes, who had at least a point in eight of nine games this season, put the Devils in a bind.
"It’s tough," Lazar said. "You look at the start he's had, I’m not going to lie, we were a little dejected when it happened. But, again, you've got to kind of turn the page when you realize he’s not coming back and say, 'All right, next man up.' We have a lot of skill in this room. We're getting tested early here, but I have full belief in this dressing room."
Neighbours gave St. Louis a 1-0 lead at 7:12 of the second period on a snap shot from the slot that beat Schmid stick side.
"It was a good forecheck and they turned it over," Neighbours said. "We quick-upped it, [Oskar Sundqvist] made a great play to [Sammy Blais] and 'Blaiser' an even better play to me. My job was just to put it in the back of the net. Great play there."