Gallagher and Galchenyuk each scored and Pacioretty had a pair of assists as the Canadiens downed the Ottawa Senators 4-1 on Saturday to go 4-1-0 on home ice.
"That was big for us," said Gallagher. "When we started that home stretch things weren't going great for us, so it was good to be able to turn it around here, get some wins and get our confidence back.
"Now we go on the road and we know what style of hockey we have to play."
The Canadiens were in a 1-5-1 funk when they returned to the Bell Centre for five games in a 12-day span. The slump, and an injury to Lars Eller, prompted coach Michel Therrien to move 20-year-old Galchenyuk from left-wing to centre and give him a pair of snipers on the wings.
The result was four goals and two assists for Galchenyuk, two goals and an assist for Gallagher and one goal and six assists for Pacioretty, who is normally the trigger man, but has been the line's top passer so far.
"That's what we're bugging him about," Gallagher said. "I guess we've got to start giving him a few. He's making it pretty easy on me and Chucky (Galchenyuk)."
Brandon Prust and Tomas Plekanec also scored for Montreal (21-11-2), which plays Tuesday against the Islanders in New York and has four more on the road before returning Jan. 6. While they are away, the Bell Centre will be used for the World Junior Championship.
Erik Condra found the back of the net for Ottawa, which was coming off a 6-2 win at home over Anaheim on Friday night. The Senators are 3-2-1 since Dave Cameron replaced Paul MacLean as head coach.
The Senators were outshot 29-25, had chances to tie the game with two power plays early in the third, but weren't able to generate any good scoring chances.
"I thought we played well enough to win," said Cameron. "They jumped us in the first period, which we knew they would do.
"They were waiting for us coming off back to back (games), much like we did (Friday) night. A 2-1 game, (Alex) Chiasson misses a real good chance, and then we have two power plays and we generated absolutely nothing, not even momentum.
"I thought the compete level was really good and we worked hard in a good building against a good team. That gave us a chance, we just weren't able to pull it out."
Pacioretty, the Canadiens leader in goals with 13 and points with 27, said there are no defined roles on the new unit, although if past performance holds, Gallagher would be the digger, Galchenyuk the playmaker and Pacioretty the shooter.
"What we like about our line is we don't have designated roles," said Pacioretty. "Anyone can get in on the forecheck, we can all be the guy in front of the net taking way the goalie's eyes.
"It's really hard for the opposition right now to get a good read on our line, knowing that we all can fill any role. It's going well. We hope to keep expanding our game, but we like how we've started off together."
The game began on an ominous note for the Canadiens as they surrendered the first goal for the 22nd time in 34 games. But after letting in a quirky first one, Carey Price shut the door the rest of the way making 24 saves.
Ottawa opened the scoring short-handed 2:50 into the game. Montreal's Sven Andrighetto fell at the Ottawa blue-line, allowing Condra to skate in and fire a harmless looking wrist shot that got through Price and dropped in the crease. Condra poked it in for the goal.
"(Price) saved us enough, so no one was pointing fingers," said Gallagher. The good news is we've given up the first goal a lot this year, so we're pretty comfortable in that position."
The Canadiens got it back at 6:38 when Prust had a harmless looking shot of his own from the right circle and it got between Robin Lehner and the post before falling just over the goal-line. Lehner finished the night by kicking out 25 shots.
A three-on-two rush saw the puck go from Pacioretty to Galchenyuk and then Gallagher, who shot the puck into an open side 7:30 into the second period.
The Canadiens added two late goals. Plekanec swept a puck in off the far post from the edge of the crease on a power play at 16:50 of the third and Galchenyuk banged in Alexei Emelin's pass at 17:34.
Ottawa heads to Washington for a game Monday night.
Notes — Pacioretty was in the Montreal lineup despite leaving Thursday's game against Anaheim and going to hospital with what looked like a serious injury. . . Eller returned after missing two weeks with an upper-body injury, while American Hockey League call-up Andrighetto bumped Michael Bournival to the press box. Joey MacDonald backed-up Price with Dustin Tokarski on a conditioning sting with the Hamilton Bulldogs, the Canadiens AHL affiliate. . . With Curtis Lazar loaned to the Canada's world junior team, Jean-Gabriel Pageau dressed for the Sens. Ottawa listed defenceman Patrick Wiercioch as a scratch. Chris Neil and Marc Methot are injured. . . The Vanier Cup champion University of Montreal Carabins were feted before the game. After the game, Montreal re-assigned goaltender Joey MacDonald to the Bulldogs. . . Price moved into a tie with Ken Dryden for games played by a Canadiens goalie with 397. The leader is Jacques Plante with 556.