Until the third period, it looked like the Washington Capitals might find a way to squeak out a positive result in a game in which they had been consistently sloppy in their own end and relied on goaltender Michal Neuvirth to prevent the Dallas Stars from taking a commanding lead.

After visiting Dallas rattled off three goals in the opening 8 minutes 5 seconds of the final frame, though, there was no doubt that the Capitals’ defensive miscues had caught up to them. The Stars captured a 5-2 victory in the lone meeting between the two teams in the 2011-12 regular season, handing Washington its second consecutive loss.

The mood of the Verizon Center dressing room was decidedly sour, since the Capitals have lost four of their past six outings, most of the defeats featuring a series of defensive lapses and allowing the opponent to outwork them.

“It takes a commitment,” veteran Mike Knuble said. “Maybe through the first five games I felt it was top to bottom a better commitment. Of late, I don’t know if we’re all committed. It’s sad to say, we all look bad because of the result because we won’t all commit.

“We look great when we’re all committing, we look all like a bunch of clowns when we don’t — very average team when we’re not all committed.”

The Capitals entered the third period tied at 2 with the Stars, but would be outworked by the Western Conference leaders. Adam Burish, Jamie Benn and Eric Nystrom all exploited soft spots in Washington’s defensive zone to put the contest out of reach at the start of the third.

“It’s good question but I don’t have the answer for this,” Alex Ovechkin said when asked why the Capitals are inconsistent. “I think everybody try and everybody wants to win and everybody wants to play how we can, maybe tonight was not our night.”

Just as a tripping penalty on Alexander Semin expired, Jeff Halpern won a faceoff but Brendan Morrow beat John Carlson and Roman Hamrlik to the puck along the boards and sent it out to Burish in the slot. Burish already had positioning on Nicklas Backstrom and was able to slip the puck past Neuvirth (31 saves) to give the Stars a lead just 24 seconds into the frame.

It was one of several goals that Coach Bruce Boudreau said demonstrated a lack of willingness to compete one-on-one against an opponent.

“I don’t know if it’s an attitude change, [or] it’s an individual type thing that has to change as far as wanting to win those one-on-one battles,” Boudreau said. “We lost the battle — first, second and the third goal that they outbattled us for pucks and they end up scoring the goal.”

Seven minutes after Burish’s goal, a thundering point shot by Sheldon Souray on the power play led to a 60-foot rebound. Benn quickly fired it back into a yawning cage, with Neuvirth still on the right side of the net after stopping the initial blast to make it 4-2. Thirty-two seconds later, Nystrom deftly skated around Carlson for an open shot in the slot and beat Neuvirth glove-hand side for a 5-2 lead.

Dallas, the first team to 10 wins in the league, got on the board first 10:32 into the contest. Michael Ryder tipped a point shot by Trevor Daley past Neuvirth.

Semin, who took two tripping penalties in the contest, evened things up when he recorded his first goal in eight games with just over four minutes remaining in the first. Set up with a no-look pass by Backstrom, Semin pumped a slap shot past Kari Lehtonen on the power play to make it 1-1.

That tie would be short-lived. Just 1:24 after Semin’s score, Ryder scored his second goal, after his teammates had helped outwork the Capitals down low. Ryder patiently waited as Neuvirth lunged for a stick save and wrapped the puck under the goaltender’s paddle for the 2-1 advantage.

In the second, Washington would tie the score at 2 on a point-shot by Carlson on a set-play off of a faceoff win by Marcus Johansson. The Capitals seemed fortunate they were able to tie the game after spending the bulk of the middle period hemmed in their own end, giving up scoring chances and the occasional odd-man rush while relying heavily on Neuvirth.

“We were fortunate to be tied at the end of two, I thought. We talked about playing one good period, and in the third period, the first 20 seconds they score a goal,” said Boudreau when asked if his team may have been too comfortable after reeling off seven wins to start the season.

“If it’s a comfort thing,” Boudreau said, “The comfort will change tomorrow.”

Capitals notes: Mike Green missed a sixth consecutive game with an injured right ankle. The defenseman initially twisted his ankle on Oct. 22 in the first period against the Detroit Red Wings. . . . Washington made a minor trade Tuesday, acquiring defensive prospect Tomas Kundratek, 21, from the New York Rangers in exchange for right wing Francois Bouchard. Kundratek is expected to be available to play for the AHL’s Hershey Bears on Wednesday.

stars 5, capitals 2