Deslauriers notched his first two-goal game since he tallied twice against Vancouver on Dec. 19.
Gallagher collected his sixth goal this season against the Wings and 31st overall. Gallagher scored in each of the four wins over Detroit.
Artturi Lehkonen had the other Montreal goal while Antti Niemi stopped 23 shots.
Dylan Larkin had a goal and an assist for the Wings. Tyler Bertuzzi and Darren Helm also scored, while Jared Coreau made 24 saves.
Deslauriers' first goal of the game gave Montreal an early lead. He redirected Noah Juulsen's shot from the point.
Larkin's individual effort tied the score late in the period. He whizzed past three defenders, then flipped a backhander just inside the goalpost for his 15th goal.
Bertuzzi's goal early in the second put the Wings on top 2-1.
The lead was short-lived. A goalie interference call against the Wings' Justin Abdelkader prevented Detroit from gaining a two-goal advantage.
A Wings giveaway in Montreal's zone resulted in a 2-on-0 break for the Canadiens. Gallagher took a pass from Jonathan Drouin and ripped a shot past Coreau for his 31st goal.
Deslauriers scored his second goal exactly three minutes later at the 14:39 mark. He made a steal near his own blue line, skated in along the right boards and fired a shot through Coreau's five-hole to give the Canadiens a 3-2 lead.
Another Wings turnover, this one at center ice, led to Montreal's next goal.
Lehkonen pounced on the loose puck, gave it up to Logan Shaw, then got it back on a 3-on-1 break and beat Coreau.
Helm narrowed Montreal's lead to 4-3 moments later. Larkin dropped off a pass near the blue line and Helm scored from the slot.
Niemi robbed Anthony Mantha in the final minute to preserve the Montreal victory.
Montreal won the first three meetings by a combined score of 20-6.
--Field Level Media
Montreal | Detroit | |
Nicolas Deslauriers 2 | Points | Dylan Larkin 2 |
Nicolas Deslauriers 2 | Goals | Dylan Larkin 1 |
Karl Alzner 1 | Assists | Dylan Larkin 1 |
N/A | Power Play Goals | N/A |
N/A | Short Handed Goals | N/A |
Antti Niemi .885 | Save Percentage | Jared Coreau .857 |
Antti Niemi 23 | Saves | Jared Coreau 24 |
Team | Shots | Goals | Power Play | Penalty Kill | Penalty Mins | Face Offs Won |
Montreal | 28 | 4 | 0-1 | 3-3 | 6 | 24 |
Detroit | 26 | 3 | 0-3 | 1-1 | 2 | 36 |