Dany Heatley, the recently formed line's left wing, added a goal and two assists as Ottawa scored four goals in each of the first two periods to match its season high for goals.
"We're using each other, we're finding each other, we're making easy plays and supporting each other and that makes the game a lot easier," said Heatley, who was named Ottawa's lone All-Star representative Saturday. "Other than that, we're skating very well and that opens up a lot of room for us."
Alfredsson, who scored his 15th goal late in the first to put Ottawa up 4-0, assisted on two of Ottawa's three previous goals in the opening period. He added two more assists on the Senators' first two goals of the second as Kelly's ninth goal 3:31 into the middle period chased Montreal's Cristobal Huet with Ottawa ahead 6-0.
"All the bounces and everything went their way," said Huet, who was added to the Eastern Conference's roster Saturday for the upcoming All-Star Game in Dallas. "It was a terrible night for us. It was embarrassing and I look at myself and I expect more from me."
All-Star Sheldon Souray scored his 15th goal 7:30 into the third, setting a record for Canadiens defensemen with his 12th power-play goal.
The eight goals were the most allowed this season by Montreal, which had previously allowed more than five only once in a 6-5 loss to Boston on Dec. 4.
"This was a big game," Souray said. "They were only three points behind us and we had a chance to jump up on them. It's not surprising that they came out as hard as they did, but for us to not have too much life or too much focus at the beginning of the game was tough because we've done that too much lately."
The Senators have won nine of 11, going 9-1-1 during that span to move within one point of the Canadiens for second place in the Northeast Division.
"They're a big rival for us, for sure," Heatley said. "It was a huge divisional game. You could feel it in the room, the guys were excited to get going today and we showed it."
Chris Higgins and Craig Rivet scored 22 seconds apart in the second, drawing Montreal to within 6-2.
Ottawa, which has won four straight, nearly blew a 5-0 lead Thursday before holding on for a 6-4 road win over the New York Rangers.
"I'm sure that was in the back of some guys' minds, but I think we learned from that," Kelly said. "We had to tighten things up in our own end and make the right plays."
Redden opened the scoring 4:29 in and Vermette made it 2-0 midway through the first.
Comrie beat Huet from the goalmouth on a pass from Heatley at 16:00 for the first of three straight power-play goals by the Senators.
Heatley's 28th goal 2:37 into the second made it 5-0, and Kelly scored Ottawa's sixth goal 54 seconds later to chase Huet.
Higgins got his 14th at 5:20, and Rivet added his sixth 22 seconds later.
Eaves got his 10th unassisted at 19:18, and Meszaros got credit for his fifth goal 23 seconds later when Souray accidentally swiped the puck into his own net when he attempted to clear the rebound.
"That was the way the game was going for us, and for them," Kelly said.
- Senators president Roy Mlakar apologized directly to Canadiens managing partner Foster Gillett, the son of team owner George Gillett, for an inappropriate recurring video scoreboard skit involving the Senators mascot forcing a visiting team's fan to jump off a ship. Canadiens GM Bob Gainey's 25-year-old daughter Laura was lost at sea in December. Neither Gainey nor George Gillett attended the game, and Foster Gillett declined comment. Mlakar addressed reporters following the game. "I humbly apologize for the big oversight that we made," Mlakar said. "There is no excuse for it."
- The Canadiens, who lost 8-2 to Carolina on Jan. 31, haven't allowed nine goals in a game since a 9-2 loss to Boston on Oct. 28, 1998.
- Guy Lapointe, Mathieu Schneider and Patrice Brisebois each had 11 power-play goals in a season for Montreal.
- The Senators have scored five straight goals in each of their last three games.