McKenna scored a power-play goal to give Toronto a 2-1 lead. He took the puck from the bottom of the right face-off dot, dangled into the slot, and his beat San Jose goalie Yaroslav Askarov with a wrist shot glove side.
Monday was the first meeting between McKenna, who was the No. 1 pick in the 2026 NHL Draft, and Ivar Stenberg, who the Sharks selected with the No. 2 pick. McKenna scored the game-winner, and Stenberg was minus-1 with one shot on goal in 14:27 of ice time.
Auston Matthews had a goal and two assists for the Maple Leafs (4-4-2), who snapped a three-game losing streak (0-2-1). Nick Paul also scored, and Sergei Bobrovsky made 30 saves to win his first home game with Toronto.
Mason Marchment scored, and Askarov made 29 saves for the Sharks (4-4-1), who are 1-3-1 in their past five games. San Jose is 1-1-1 on a current six-game road trip and will face the Montreal Canadiens in the second game of a back-to-back on Tuesday.
Marchment gave the Sharks a 1-0 lead at 13:54 of the first period. Tyler Toffoli floated a puck from the left point to the net, where Marchment gloved it down at the top of the crease and lifted a backhander over Bobrovsky's left pad.
Matthews tied the game 1-1 with a power-play goal at 19:48 of the second period. Kirill Marchenko was behind the net and found Matthews in the slot with a pass, and his one-timer beat Askarov over the blocker.
Paul added an empty-net goal at 19:20 of the third period after he raced down the right wing and scored from the top of the circle for the 3-1 final.
