Joseph Woll made 29 saves for the Maple Leafs (45-25-4), who were coming off a 3-1 win at the Los Angeles Kings on Saturday.
"As a full team, we did a great job," Woll said. "We had some amazing blocks by our defensemen, and just a good job staying to our structure, staying patient and getting a tight win."
Toronto is in first place in the Atlantic Division, three points ahead of the Tampa Bay Lightning and Florida Panthers. The Maple Leafs have played one more game.
"I thought the team competed hard tonight," Toronto coach Craig Berube said. "I thought we were a little tired and gassed, or it looked like it anyway, but we did a good job defending. We did what we had to do to win the game."
Leo Carlsson and Sam Colangelo scored, and Lukas Dostal made 20 saves for the Ducks (32-33-8), who had won two in a row and three of four.
“I thought we battled hard the whole game," Anaheim defenseman Jackson LaCombe said. "They’re a really good team and I thought we stuck with it the whole time. They got a good bounce with the tip at the end and we just couldn’t get one back.”
Toronto took a 3-2 lead when Lorentz scored on a deflection from the side of the crease at 11:35 of the third period.
"He is a down-low player in the offensive zone who knows what he needs to do to be successful," Berube said of Lorentz, who has four game-winners among his seven goals. "He is around the net."