Steve Oleksy delivers a nasty check on Ottawa’s Jean-Gabriel Pageau in the first period, but little else went right for the Capitals in the opening frame. (Fred Chartrand/ASSOCIATED PRESS)

The Washington Capitals arrived here the hottest team in the NHL, unbeaten since the calendar turned to April. They were overflowing with confidence, displaying both defensive acumen and offensive prowess.

Thursday night, for the first time in several weeks, the Capitals played without the precision that helped them race up the Eastern Conference standings. From the start against the Ottawa Senators, Washington struggled to complete simple plays and appeared a step — sometimes two — behind in a 3-1 loss.

The defeat snapped their winning streak at eight and was just their third in the past 15 games. It also came on the same night the Winnipeg Jets defeated the Carolina Hurricanes, 4-3 in overtime, allowing them to pull within two points of Washington and the Southeast Division lead.

“Our execution was off. We were just sloppy tonight,” Coach Adam Oates said. “That’s the first time we’ve done that in a long time. We tried to get it going at times, but I don’t think we sustained it enough.”

More concerning than the loss, however, was that top center Nicklas Backstrom didn’t take a shift in the final 7 minutes 16 seconds of the third period.

As the Capitals likely head into the playoffs, the Post Sports Live crew debates whether the Capitals are one of the top three teams in the Eastern Conference. (Post Sports Live)

Backstrom took a Mike Green slap shot off his left arm and Oates said the 25-year-old Swede will be evaluated further Friday. The injury’s timing could be less than ideal for the Capitals, who had finally established a rhythm in their play with a fairly consistent lineup.

“It caught him in the arm,” Green said. “He’s all right, but it definitely gave him a bruise so I hope everything’s okay with him.”

From the opening faceoff, the Capitals sabotaged their own efforts by taking two penalties – Mike Ribeiro for boarding and Green for tripping — in the first 6:22. Washington thwarted both power plays and held the Senators without a shot but largely struggled to establish much in the way of possession.

By the end of the opening period, Ottawa had outshot the Capitals, 11-4, and the visitors appeared to be chasing their foes around the defensive zone. The Capitals were being beaten to loose pucks and struggled to connect on routine passes.

Perhaps the best example came with less than three minutes remaining in the period when Guillaume Latendresse beat Green to an icing touch-up and sent the puck out in front. Martin Erat picked it up, then turned it over, creating a point-blank chance for the Senators’ winger.

“Right away start no emotion,” said Capitals winger Alex Ovechkin, who finished with four shots on goal and a minus-3 rating and had no points for just the third time in the past 19 games. “In that kind of position where they get power play right away, two power plays, they get momentum in the game and they have more, they involved in the game more than us.”

Ottawa came out with the same dominance early in the second period, creating sustained pressure and chances. Kyle Turris put the Senators up 1-0 with 1:15 gone in the middle period with a wrister from the left circle that deflected off Karl Alzner’s stick and slipped under Braden Holtby’s right arm.

The Senators continued to dictate the pace of the contest and hem Washington in its own zone for much of the next 10 minutes. The only relief came when Erik Condra ran over Holtby and received a minor penalty for goaltender interference, giving the Capitals an opportunity to realize there was another end of the sheet of ice.

Despite being thoroughly outplayed for the first half of the game, the Capitals tied the contest at 1 at the 11:14 mark of the second. Jack Hillen’s shot from the point deflected toward Erat as he made his way into the left circle. Erat smacked the bouncing puck toward the net, where Ribeiro was able to bat it past Craig Anderson’s glove.

An uncharacteristic puck-handling blunder by Holtby would quickly erase any potential momentum the Capitals had established. Holtby went behind the net to retrieve the puck but didn’t look as he sent a pass out toward the right boards intended for Alzner. The pass was too far for the defenseman to reach and instead went to Cory Conacher, who fired into the empty net before Holtby could regain his positioning for a 2-1 Senators lead.

“It’s just one of those rushed plays. Had to make a blind pass and I didn’t execute it on the tape,” said Holtby, who stopped 35 of the 37 shots he faced. “That’s one of those that you want back, but you can’t let it dwell on you. It happens. They had a hard forecheck all game and they caused that turnover.”

Oates said Holtby’s miscue was a prime example of how nothing went as intended for the Capitals against Ottawa Thursday night.

“That’s indicative of our game tonight,” Oates said. “That’s a simple play for him. That’s a play he’ll make 100 times in a row and I think his execution was off too.”

While the Capitals had a few chances to even the score in the third period, trying to mount a comeback against Anderson, owner of the league’s best save percentage (.949) and goals against average (1.52), was a daunting challenge, and the Capitals only forced him to make 18 saves.

Turris added an empty netter with 1:27 remaining to ice the contest, securing Ottawa’s fourth consecutive victory.

“All in all, we weren’t in the game I didn’t feel,” Oates said. “We were fighting an uphill battle just with our execution, decisions and you’ve got to give them some credit.”