The Washington Capitals knew they were living dangerously before the opening puck drop against the Montreal Canadiens. With only 11 healthy forwards and seven defensemen dressing at Capital One Arena, the game Friday would be another test of the team’s ability to handle adversity.

But for once, the obstacles — players double-shifting, defenseman Tyler Lewington being used briefly as a forward — proved a bit too much to overcome.

Washington found itself down four goals in the second period en route to a 5-2 loss that was its first defeat in regulation since Oct. 14, ending a 13-game point streak.

“We made a push at the end,” Capitals Coach Todd Reirden said. “But we weren’t sharp. For the most part we’ve been really consistent this year. That game we were off.”

The Capitals (14-3-4) came to life briefly with two goals in the third period — one from captain Alex Ovechkin on a power play at the 5:34 mark and another from Evgeny Kuznetsov with 4:22 left, but Washington got no closer.

“We just didn’t execute. . . . We just weren’t at our best in a lot of areas with the puck, without the puck,” center Lars Eller said. “We weren’t connecting, and it just wasn’t our game.”

Ovechkin’s goal was the 672nd of his career and was assisted by John Carlson, who recorded his 31st point (eight goals, 23 assists) of the season. Kuznetsov’s goal came on a skilled breakaway. He beat goaltender Carey Price to cut Montreal’s lead to two before Tomas Tatar scored an empty-netter with 2:31 left.

Neither team found the back of the net in the opening 20 minutes, but the Canadiens found a spark in the second period, scoring four goals after Ovechkin’s thunderous hit sent Jonathan Drouin off the ice.

Drouin returned to start the third period. Though the hit is the type of play the Department of Player Safety tends to examine, the likelihood of any discipline for Ovechkin appears to be low; no penalty was called.

“It’s hockey,” Ovechkin said after the game about the hit. “It’s not ballet. . . . I don’t know, it’s a hockey play. He didn’t see me. It’s a clear hit. Nothing to say.”

Center Phillip Danault started the scoring for Montreal at the 6:22 mark of the second period after he was left all alone in front of rookie goaltender Ilya Samsonov. Shea Weber scored less than three minutes later. Jordan Weal scored at 11:41, and Nick Suzuki all but sealed it at 14:42. All of the goals came at even strength.

Samsonov, who had 15 saves in the first period, stopped 35 of 39 shots on the night. It was Samsonov’s second straight game in which the opponent took at least a 3-0 lead; Arizona went up, 3-0, Monday before the Capitals stormed back, only to lose, 4-3, after a shootout. He now has a 5-2-1 record on the season. Goaltender Braden Holtby will start Saturday at Boston in the second leg of a back-to-back.

The Capitals played with only 11 forwards Friday night after Nic Dowd and Carl Hagelin were both ruled out with upper-body injuries. Both are considered day-to-day. Reirden said Friday morning that he was unsure whether either would return Saturday. Facing a tight salary cap, the Capitals only could afford to call up Lewington, who carries the lowest salary cap hit ($675,000), instead of a forward from Hershey of the American Hockey League.

Hagelin has missed four straight games, while Dowd was injured in Wednesday’s 2-1 shootout win against Philadelphia. He suffered a gash on his hand while being called for a tripping penalty. He left the ice to get treated and returned to the bench but did not take another shift.

Without Dowd or Hagelin, it was crucial for the Capitals to play at even strength Friday as much as possible. The team was able to do just that most the game, having to kill only one Canadiens power play. It won the special teams battle with Ovechkin’s one-timer.

The Capitals do not want to play with only 11 healthy forwards more than necessary and are expected to make additional moves ahead of the game against the Bruins.

“You know at some point that’s going to happen,” Reirden said. “It’s important to fairly evaluate your team. That was where we were at. We weren’t as good as we could be tonight. There’s been stretches where we’ve not been as good as we would’ve liked at other points and we’ve been able to find it.”