The match-up had been highly anticipated following the hostilities that had broken out between the two teams Thursday in a game that featured both goalies exchanging punches.
Dany Heatley had a goal and two assists, while Christoph Schubert, Chris Kelly and Daniel Alfredsson also scored for Ottawa. Ray Emery faced 36 shots.
Henrik Tallinder, Derek Roy, Jason Pominville and Thomas Vanek scored for the Sabres.
The sellout crowd of 20,040 at Scotiabank Place had to wait until the second period to see any retaliation from the Senators (36-22-4), who were still upset over Andrew Peters fighting with Emery.
Senators enforcer Brian McGrattan, dressing for the first time in 10 games, dropped the gloves with Peters three minutes into the second to the delight of the home crowd.
Just over five minutes later Chris Neil and Buffalo's Adam Mair went toe-to-toe. The Senators had a score to settle with Mair, who they believed crossed the line when he brought up the deceased Dan Snyder to Heatley last Thursday. Snyder died in a car accident just over three years ago. Heatley had been driving the car.
The Sabres (41-16-5) opened the scoring just two minutes into the game as Tallinder had a wide-open net after Emery was caught out of position.
Spezza tied the game after taking a deft pass from Heatley to beat goalie Martin Biron high stick side with just over five minutes remaining in the period.
Thomas Vanek missed an opportunity to give the Sabres the lead, as he was unable to convert on a penalty shot. Emery has faced four penalty shots this season, allowing the three previous shots.
The Senators then went on to score three unanswered goals in less than two minutes, which chased Biron from the game.
Heatley, on the power play, beat Biron stick side and 61 seconds later Schubert roofed it over the sprawling goalie. Kelly completed the outburst scoring on his backhand.
Roy scored late in the period to cut the lead in half and Pominville scored early in the third to make it a 4-3 game. But the Senators regained the two-goal cushion on Alfredsson's 22nd of the season.
The Sabres continued to fight back and Vanek caught a lucky break when Emery inadvertently kicked the puck in to make it a 5-4 game. With his second of the night, Tallinder tied the game with just over eight minutes remaining.
Spezza, with his 25th of the season, scored the winner with 4:07 remaining.
With the victory the Senators won the season series with a 5-2-1 record.
Notes: Ottawa D Joe Corvo was a healthy scratchaBuffalo coach Lindy Ruff was fined US$10,000 by the league SaturdayaBuffalo was without C Chris Drury (head day-to-day), Tim Connolly (concussion, indefinite), RW Maxim Afinogenov (wrist, early April), C Paul Gaustad (ankle, season), RW Ales Kotalik (knee, late March), C Jiri Novotny (ankle, indefinite), LW Daniel Paille (finger, mid-March), D Jaroslav Spacek (hand, late February)a Colin Campbell, the league's director of hockey operations, was in attendance.