Capitals defenseman John Carlson will miss his first game of the season Friday night. (Nick Wass/Associated Press)

The Washington Capitals will be down two regular defensemen for at least Friday night’s game against the visiting Columbus Blue Jackets. John Carlson will miss his first game of the season with an undisclosed lower-body injury, and Brooks Orpik, who has missed the past four games with a lower-body injury, will be sidelined for at least six more after being placed on long-term injured reserve retroactive to Oct. 28.

The Capitals recalled defensemen Jonas Siegenthaler and Aaron Ness from the American Hockey League, and Siegenthaler, the organization’s 2015 second-round pick, will make his NHL debut against the Blue Jackets. He was among the last cuts at training camp, and he’ll play on the third pairing with Madison Bowey on Friday.

“I’ve dreamed about this all my life, and I’ve never felt this happy in my life,” Siegenthaler said. “It’s something really special for me. I worked hard to get here, and yeah, it’s so special I can’t really describe it.”

Carlson’s injury is a blow, considering he has averaged a team-high 26 minutes while playing on the top power-play unit and also the penalty kill. Through 14 games, he has five goals with 13 assists. That he was injured came as a surprise after he played 28:17 in Washington’s 2-1 win over Pittsburgh on Wednesday, assisting on T.J. Oshie’s game-winning goal late in the third period. Coach Todd Reirden was vague about what happened, but he said he was hopeful that Carlson would play in the Capitals' next game, Sunday against the visiting Arizona Coyotes. Defenseman Matt Niskanen will take Carlson’s place at the point for the top power-play unit.

The Capitals initially said Orpik wasn’t expected to miss much time and was day-to-day, but he hasn’t skated in nearly two weeks. With the Capitals facing salary cap constraints, moving him to long-term injured reserve allowed them to afford to recall Siegenthaler and Ness. Orpik won’t be eligible to come off injured reserve until Nov. 21 vs. Chicago.

Washington will be using three defensemen with fewer than 100 games of NHL experience Friday night, concerning for a team that is allowing 3.5 goals per game, sixth-most in the league.

“It’s a great opportunity tonight for some young players against a very hard-working, hard-forechecking team,” Reirden said. “It’ll be a good test, and for me, it’s about giving these guys opportunities and [seeing] what they do with them.”

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