Mike Fisher scored two power-play goals and Dean McAmmond scored once while shorthanded and added another at even strength as the Senators cruised to a 5-1 victory over the Maple Leafs.
The Senators (39-23-6) had lost their last three games after blowing third-period leads, but the sold-out crowd of 20,018 at Scotiabank Place watched them take the lead early and run away with the front end of the home-and-home series.
"We played well enough over parts of the last three games. Tonight, we were complete," said Senators coach Bryan Murray, whose team lost to Atlanta, Chicago and Pittsburgh in the last seven days after leading heading into the third period.
On Thursday, the Battle of Ontario turned out to be a one-sided affair after Fisher beat Leafs goaltender Andrew Raycroft twice in the first and McAmmond added to the misery during a Toronto power play early in the second.
With the Senators up 4-1 in the third on a power-play goal by Tom Preissing, McAmmond iced the game with his second of the contest.
"We just learned from this week," Fisher said. "We felt confident on the bench, we kept pressing and had the killer instinct we needed to."
Daniel Alfredsson added three assists and Ray Emery stopped 28 shots for Ottawa.
Jason Spezza returned after sitting out Ottawa's shootout loss to Pittsburgh on Tuesday with a back injury and contributed two assists while Dany Heatley also had an assist to extend his points streak to 13 games (10 goals, 10 assists).
The beating improved Ottawa's record to 5-1-1 against the Leafs (32-27-9) for the season. The Senators have won 12 of the last 15 regular-season meetings between the teams, outscoring Toronto 67-35 in the process.
Alex Steen had the lone goal for the Leafs, who lost for the second time in three games and sixth time in nine contests.
"You have to give them a lot of credit, they came out flying," said Raycroft, who finished with 35 saves. "They had more jump, they were on the puck faster than us, especially in our own end and when they got on a roll, we weren't able to stop them."
Toronto also suffered a blow to its playoff hopes, losing its hold on the eighth and final playoff spot in the Eastern Conference standings. Although the Leafs are tied with the New York Rangers, who won Wednesday, and Carolina, which was idle, with 73 points, both the Rangers and Hurricanes have 33 wins and New York even has a game in hand.
Special teams made a huge difference. The Senators went 3-for-6 on the power play; Toronto was 0-for-8.
"That's the big story, I guess," Steen said. "They got three power-play goals and we got nothing."
The teams meet again Saturday at Air Canada Centre.
The Leafs are just 3-for-39 against Ottawa with the man advantage this season and, according to coach Paul Maurice, miss defenceman Tomas Kaberle, who's out with a concussion.
"We're struggling," Maurice said. "We're not (dangerous) and things aren't easy for us."
Toronto allowed just 24 shots in total in shutting out the Washington Capitals 3-0 on Tuesday, but the Leafs were outshot 23-7 in the opening 20 minutes.
After the Leafs were called for too many men on the ice, Fisher took a pass from Peter Schaefer at the side of the net and beat Raycroft to open the scoring at the 5:13 mark.
Then, with Mats Sundin off for cross-checking, Fisher's centring pass went off the skate of Toronto's defenceman Carlo Colaiacovo and past Raycroft to make it 2-0.
At the other end, Bates Battaglia had Emery beat but fired a shot off the post and was later stopped from close range by the Senators goaltender.
The Senators' 23 shots were a season high.
"It was nice to get off to the good start, get some cycling going and get some chances," Alfredsson said.
Toronto had a four-minute power play that carried over to the second thanks to a high-sticking penalty to Spezza and failed to take advantage.
With the Leafs back on the power play, they gave up a short-handed goal to McAmmond after some strong work by Alfredsson.
Steen cut the lead to 3-1 midway through the period, but Preissing scored on the power play after taking a cross-ice pass from Spezza before the second was over.
Spezza now has at least a point in the past 12 games he's played.
McAmmond capped off the scoring with his second of the night early in the third.
The Leafs had one good chance with time running out, but Emery stopped Travis Green from close range.
"We kept pressing and kept forechecking," Alfredsson said. "We limited their chances, especially five-on-five. We didn't give them any momentum."
Notes: Heatley's assist was the 200th of his career . . . Toronto forward Kyle Wellwood (hernia surgery) skated Thursday and could return for Saturday's game . . . In addition to Kaberle, the Leafs also scratched defenceman Wade Belak and forward Boyd Devereaux . . . Defenceman Lawrence Nycholat, acquired from Washington on Feb. 26, has yet to dress for the Senators, who also scratched forwards Brian McGrattan and Patrick Eaves.