Brooks Laich scored to put the Capitals up 3-1 in the opening period, but the lead would not stand up as Washington drops its fourth straight. (Jonathan Newton/The Washington Post)

For 20 minutes Wednesday night, the Washington Capitals looked like they might be ready to snap out of their self-inflicted doldrums.

But the Capitals again couldn’t get out of their own way. Through turnovers, an inability to put the puck deep and a parade to the penalty box that lasted all Thanksgiving eve, Washington squandered a two-goal lead and fell, 6-4, to the Ottawa Senators at Verizon Center.

The script of this loss — Washington’s fourth straight — left Coach Adam Oates fuming afterward, visibly irritated as he discussed the same sorts of mistakes the Capitals have been making all season. That this performance followed an encouraging outing in Toronto, where the Capitals lost, 2-1, in a shootout Saturday, made it all the more aggravating for the second-year coach.

“We played lousy tonight. Lousy,” Oates said. “We get a lead, and we still don’t do the right things even though on the third goal that we scored we get the goal from doing the right thing. [Brooks Laich’s] goal came from what we talk about all day long. We’re up 3-1, and the next shift we turn it over twice. That’s mental to me.”

The relatively strong start was a change of pace for the Capitals, who have struggled at the outset all season. They recorded three goals in a span of 2 minutes 43 seconds as players other than Alex Ovechkin, who was held to an assist and three shots, joined in on the offense for the first time in four games.

Eric Fehr put the Capitals ahead 1-0 when he drove toward the front of the net and was in the precise spot to gain possession when gritty center Michael Latta was upended as he cut through the left circle. Fehr fired a shot inside the right post past Craig Anderson (29 saves) with 12:10 gone in the first.

Ottawa answered quickly on a power-play goal by Bobby Ryan, but Marcus Johansson regained the lead for the Capitals 38 seconds later when he scored on a tap-in on a power play to make it 2-1. Then, 46 seconds after Johansson’s tally, Brooks Laich scored one after an effective cycle against the team that drafted him. His quick backhander gave Washington a 3-1 lead at 14:53, but that’s about where the positive momentum stopped for the home team.

“The rest of the game we saw a very bad hockey team: bad decisions, bad penalties, getting outworked,” Laich said. “We were very unstructured the last 40 minutes, and it’s unfortunate. I thought we played maybe one of our best first periods of the season.”

With a two-goal advantage and an opportunity to play from a position of strength for the first time in more than a week, the Capitals unraveled. Of all the ways to defend the two-goal lead, taking more penalties (five) than shots (three) in the second period and struggling to make the right play isn’t a route that leads to success. Ottawa outshot the Capitals 19-3 in the middle period, erasing its deficit in the process.

Veteran defenseman Chris Phillips scored the Senators’ second power-play goal of the night to draw them within one when he beat Holtby cleanly high, glove side with a booming slap shot.

Just past the midway point of the period, the Senators picked off a centering pass deep in their own zone and raced into the opposite one. Colin Greening fired through a screen of Karl Alzner and Ottawa agitator Chris Neil, and the shot beat Holtby at 10:36. Less than a dozen minutes into the second period, Washington’s lead was an afterthought.

“It’s always dangerous when you get a lead,” Fehr said. “You stop playing the way you played to get that lead. You sit back. That’s not the way to play hockey. We know better, and it cost us the game.”

That lack of mental fortitude and the absence of a commitment to adhere to a game plan are what Oates is most frustrated with.

“You’re up 3-1. Maybe you think it’s an easy night, and then all of a sudden they get the puck again,” Oates said. “We got the goals from doing the right things. We’ve got to be disciplined in who we are — even our fancy guys, probably from the fancy guys first. Some guys they know that they’ve got no choice [but to stick to simple plays], but guys with choices still gotta put it deep.”

Mika Zibanejad gave Ottawa its first lead of the night at 4-3 6:05 into the third on a power-play goal with Fehr in the box for tripping. It marked the first time this season Washington had allowed three power-play goals in a game. While John Carlson scored with 3:27 remaining in regulation to give the Capitals a glimmer of hope, it was extinguished when Zack Smith scored 64 seconds afterward for the game-winner.

“We had them. We were close to putting our stamp on it, but we let them back,” Carlson said. “It’s tough. We need wins right now, and this is certainly one that we can look back on and make sure it doesn’t happen again because it’s not a good loss.”