"That was a big point to give away," Stars center Tyler Seguin said. "I mean we obviously needed it a lot more than them. It's disappointing."
Nazem Kadri scored, and Tyler Bozak and Marner scored in the shootout for the Maple Leafs (41-22-7), who won their 11th straight home game, the most in their history.
Seguin, Jamie Benn, Radek Faksa, Remi Elie and Brett Ritchie scored, and Kari Lehtonen made 26 saves for the Stars (38-26-7), who trail the Minnesota Wild by two points for third in the Central Division and are one point ahead of the Colorado Avalanche, who are tied with the Anaheim Ducks (82 points) but hold the second wild card because they've played two fewer games.
"It's tough, we gave that lead away in the third," Stars forward Devin Shore said. "We said all the right things in the room, how we wanted to keep it pushing because I thought our second period was really good. It stings. At this stage, it's all about results. We didn't get it done so we've got to turn it around."