Patrick Eaves scored a goal and an assist and Dany Heatley added two helpers as the Senators defeated the Toronto Maple Leafs 4-1.
Martin Gerber had a solid night between the pipes for the Senators. The Swiss goaltender made 33 saves, including several from close range to earn his first win for his new team.
"You want to do well with your new team. Expectations are high. I'm pretty happy we got that win," said Gerber.
The Senators signed Gerber in the off-season to a three-year, $11.1-million US free-agent deal in the hope of ending their search for a No. 1 goaltender.
"Martin gave us a chance to win the game, especially early on," said Senators captain Daniel Alfredsson.
The Leafs, who honoured Hall of Famers Borje Salming, Red Kelly and the late Clarence (Hap) Day before the game, continued their struggles against the Senators in the regular season.
Toronto lost seven of eight games to the Senators last year and didn't fare any better Wednesday night with Prime Minister Stephen Harper and his 10-year-old son Ben among the sold-out crowd of 19,520.
The Leafs defence looked especially sloppy, turning the puck over several times to allow Ottawa more scoring opportunities.
The Senators opened the scoring on the power play in the waning moments of the first period.
Toronto goaltender Andrew Raycroft stopped the initial shot by Tom Preissing, but couldn't handle the rebound off the stick of Eaves.
Ottawa went up 2-0 at 10:13 of the second when Chris Neil took a nifty pass from Dean McAmmond, raced into the slot and deked Raycroft with a backhand to the stick side.
The Senators increased their lead to 3-0 1:16 later after Christoph Schubert's shot at the side of the net trickled between the pads of Raycroft and barely slid beyond the goal-line.
"That was a weird one," said Raycroft. "It went off somebody and caught my back leg."
The Leafs finally scored their only goal of the game with less than eight minutes remaining in the second.
Captain Mats Sundin was awarded the first penalty shot of the NHL season when defenceman Anton Volchenkov dragged the Leaf centre from behind on the breakaway.
Sundin then managed to beat Gerber with a shot that eventually squeezed between the pads of the Senators netminder and into the open net.
"It's tough to lose the home opener, but I don't think it's as bad as the scoresheet says," said Sundin.
Alfredsson then iced the game for Ottawa, scoring an empty-net goal with only 23 seconds remaining in the third.
Raycroft, acquired by the Leafs in an off-season trade with the Boston Bruins for fellow netminder Tuukka Rask, was the lone bright spot for Toronto.
Raycroft made 32 saves, including a splendid stop off Heatley during a third-period breakaway.
With files from the Associated Press
Toronto produced an unexpectedly good night of special-teams play that spearheaded a convincing 6-0 win over the Senators in the back leg of a home-and-home series against its Northeast Division rivals.
The Leafs, who went 0-5 with the man advantage during their 4-1 defeat to Ottawa Wednesday at the Air Canada Centre, scored twice on the power play and also added another short-handed goal.
Darcy Tucker and Chad Kilger led Toronto with two goals apiece, while Kyle Wellwood led all scorers with four assists.
Leafs captain Mats Sundin also had a productive night, finishing the game with two assists.
Goaltender Andrew Raycroft had another solid performance for Toronto, stopping all 34 Ottawa shots. Despite Wednesday's lopsided defeat to the Senators, Raycroft made 32-of-35 saves.
"It's nice to get it out of the way," said Raycroft, who stopped 34 shots. "You don't want to go 0-2 to start the season, then the sticks start tightening up."
Turnabout for the Leafs
Missed scoring opportunities, an inept power play and poor defensive coverage contributed to Toronto's eighth loss in its last nine meetings against Ottawa prior to Thursday's game.
But this night proved a complete reversal for the Leafs.
Toronto surprised Ottawa with a short-handed goal at 11:03 of the first period to open the scoring.
With the Senators pressing in Toronto's zone, Chad Kilger broke up ice, took a pass from Mike Peca and blasted a low shot that beat goaltender Martin Gerber under his left pad.
"It was nice for us to get out and get a lead and see how we handle it," Kilger said.
The Leafs took a 2-0 lead more than three minutes later on the power play. Defenceman Bryan McCabe fed Darcy Tucker, who snapped a shot over the shoulder of Gerber to the short side.
Raycroft bailed out his teammates following a turnover in Ottawa's end that turned into a breakaway by Peter Schaefer.
As Schaefer raced in on Raycroft, the Toronto netminder alertly used a poke check to steer the puck out of harm's way with less than two minutes remaining in the first.
"I thought he played well [Wednesday]," Toronto coach Paul Maurice said of Raycroft, who drew some criticism from the media following the season-opening loss. "And I thought this was a just result."
Kilger notched his second goal of the game at 5:42 of the second period to give Toronto a 3-0 advantage.
Gerber left the puck behind the net following a Leaf shoot-in, expecting defenceman Wade Redden to pass by. However, Alex Steen beat the Ottawa defenceman to the puck and flipped a pass in front to Kilger, who converted a one-timer past Gerber.
The Leafs increased their lead to 4-0 with their second power-play goal less than four minutes later. Tucker grabbed the rebound in the slot and slid the puck under Gerber for his second goal of the night.
"We go in there and win and they pat themselves on the back it looked like," Senators coach Bryan Murray said of his team. "We talked about being a team that wants to work and play hard and we didn't do a very good job of that."
Forward Alexei Ponikarovsky gave the Leafs a five-goal lead with less than three minutes remaining in the second, redirecting Sundin's shot in front of Gerber.
After Gerber allowed five goals on only 24 shots through the first two periods, Senators coach Bryan Murray replaced him with Ray Emery to start the third.
The Leafs finished off the scoring in the third period on a goal by Bates Battaglia.
With files from the Canadian Press
And for the 7 remaining Sabres fans in greater Moncton...
By JOHN WAWROWAP Sports Writer
BUFFALO, N.Y. (AP) -Suspense, stunning goals and a shootout: Daniel Briere and the Buffalo Sabres certainly knew how to put on an entertaining show in their home opener.
After spending much of the first 59 minutes trailing the Montreal Canadiens, the resilient Sabres scored twice in the final five minutes and then completed the comeback with a 5-4 shootout victory on Friday.
"It's not a situation we want to be in every game," the Sabres' co-captain said with a big grin. "But it's definitely a lot of fun. ... We found a way to win. We're not quitters."