Detroit took the lead with two goals in the second period, when it limited Toronto to five shots on goal.
"I didn't think we had the same compete level in the first period that we've had recently," Red Wings coach Jeff Blashill said. "We talked about it between periods, and we were much better in the second."
DeKeyser tied it 1-1 at 5:22, getting to a loose puck in the left face-off circle and flipping it past McElhinney for his first point of the season in his 15th game.
Daley put the Red Wings ahead 2-1 at 11:22, keeping the puck on a shorthanded, 2-on-1 break and beating McElhinney with a wrist shot from the left hash marks. It was Daley's third shorthanded goal in 924 NHL games.
"I thought we had a good first period, and we were still playing well into the second period," Maple Leafs coach Mike Babcock said. "Once they got the first goal, we unraveled a little, and after the shorthanded goal, we were chasing the game."
McElhinney said he was expecting Daley to pass to Dylan Larkin rather than shoot.
"You have to play the odds in a situation like that," he said. "Give Daley credit for making a good shot."