Labanc scored 32 seconds later to cut it to 2-1 at 16:15. He skated down the left wing on a 2-on-1 and scored on a wrist shot from the left circle.
"We kind of gave up two points," Labanc said. "We had a good 15 (minutes) and then the second, third period, kind of let the game go. We didn't create as many chances as we would like, but this game's behind us. We've got to get ready for Philadelphia and make sure everybody's ready. We can end this road trip on a pretty good note."
The Sharks had a chance to tie it late in regulation with Kahkonen pulled for the extra attacker, but Erik Karlsson hit the post with 2:00 remaining, and Blackwood denied Timo Meier on a slap shot with 12 seconds left.
"He's made the big saves when we needed them and, again tonight, those last couple of minutes," Ruff said. "He found some pucks through traffic that made the difference to allow us to win that game."
NOTES: Devils forward Jesper Bratt had the secondary assist on Mercer's goal, his eighth in five games this season. ... The Sharks were 2-for-3 on the penalty kill and are 22-for-23 this season. ... Blackwood has allowed four goals on 59 shots in the past three games after allowing four goals on 24 shots in a 5-2 loss at the Philadelphia Flyers on Oct. 13. ... Labanc, who was born in Brooklyn, New York, played his minor hockey with the New Jersey Rockets at Prudential Center before joining USA Hockey's National Team Development Program. "It's a pretty special building to score a goal for me," he said.