Brady Tkachuk had the other goal for the Senators. Jake Sanderson chipped in two assists.
Anton Forsberg made 35 saves in his first game action since suffering medial collateral ligament tears in both knees Feb. 11 in a 6-3 loss to the Edmonton Oilers.
William Lagesson and Alex Steeves scored for Toronto. Keith Petruzzelli made 25 saves on 28 shots through two periods, while Dennis Hildeby turned aside all four shots he faced in the third.
The first two periods were almost mirror opposites of each other. The Senators had a 24-7 shot advantage and 2-0 lead after the first period. The Leafs outshot the Senators 17-4 in the second period and tied the game 2-2 before a late power-play goal gave the Senators a 3-2 lead after two periods.
Tkachuk opened the scoring for Ottawa with a power-play goal almost halfway through the first period. Tkachuk collected a rebound at the side of the net and tucked it past Petruzzelli for a 1-0 lead.
Stützle increased that lead to 2-0 with a snap shot from the top of the circle at 18:01.
Lagesson beat Forsberg high to the stick at 9:32 of the second before Steeves scored from the slot on a power play at 17:50 to tie the game.
Stützle scored his second of the game, this one on the power play, just 50 seconds later with a quick shot off the post and in past Petruzzelli.
The Senators finished 2-for-4 on the powerplay, while the Maple Leafs were 1-for-6.
Senators forward Shane Pinto remains out of camp as he and the Senators have yet to come to agreement on a new contract for the unrestricted free agent…Senators forward Josh Norris didn’t dress as he has worn a yellow non-contact jersey since camp opened.