A month ago, Mathieu Perreault was fighting for a spot on Washington’s opening night roster in training camp. After cracking the NHL roster out of camp for the first time in his career, Perreault has five points (three goals, two assists) in five games.

His two-goal effort against the Red Wings Saturday night keeps reminding Coach Bruce Boudreau of what Perreault, who was praised for having the best training camp performance of any player, can bring to the Capitals’ lineup.

“It keeps going, like that little energizer bunny,” Boudreau said.

Perreault’s three goals have come in the last two games and his first tally in the 7-1 win over Detroit came at a critical juncture to help provide momentum heading into the third period. After the Red Wings cut Washington’s lead to two goals in the second and challenged to draw closer during a stretch of four power plays in succession, Perreault upped the lead to 4-1 with just 7.6 seconds remaining in the period.

Matt Hendricks’s shot was tipped by a defenseman and the puck squeaked through Ty Conklin’s pads. The puck lay unattended in the blue paint behind the Red Wings’ goaltender, where Perreault was ready to sweep it over the goal line.

“I saw the puck tip and I saw his pad was kind of open so I knew it was going to trickle behind it. So I went there right away,” Perreault said. “I like to sneak behind their D-men like that. If you look a lot of goals I score are tap-ins behind their D-men. This is where I like to hang, and I saw the puck was there and I tapped it in.”

That goal helped the Capitals knock the Red Wings, playing in the second of back-to-back games, on their heels a bit for the third.

Perreault finished another fourth-line chance at 11:19 of the third period. Hendricks won a faceoff in the offensive zone and pushed the puck to Jeff Halpern, who found Perreault open in the slot for an easy wrister.

Perreault is the only member of the fourth line who has scored a goal, but seven games into the 2011-12 season, the trio has combined for 10 points.