"It means a lot — obviously key to be successful down the road," center Nicklas Backstrom said of the balanced scoring. "That is something that we've been trying to do the whole year and trying to work on every day."
The Capitals improved to 24-5-5 and have won five straight games on the road.
Lars Eller scored 1:58 into the third period to break a 1-1 tie; it was his first goal since Nov. 27. Garnet Hathaway followed it up less than a minute later with a goal that would become the game-winner. Hathaway was denied on his first shot, but the puck hit his leg as he flew through the crease and trickled into the net for his fifth goal of the season.
Tampa Bay cut the lead in half when Jan Rutta's snipe beat goaltender Ilya Samsonov with 8:44 left, but the Lightning drew no closer. T.J. Oshie responded with a wraparound goal with 7:42 remaining, and Tom Wilson added a late empty-netter. It was Oshie's 14th goal of the season and his third goal in two games after his two-goal night in a 3-2 win against Boston on Wednesday.
"It's important getting contributions throughout the lineup," Brendan Leipsic said of the team's balance. "It is not going to happen like that every night, but coming into a tough building, Lars got us going there to start the third. . . . Got back to our game, got pucks deep."
Tampa Bay's best period was the second, with Brayden Point scoring on the power play to tie it at 1. In a penalty-filled period, the Capitals killed off three other Lightning power plays and fended off multiple extended stretches in their own end.
"Second period, Sammy was unreal," Leipsic said of the Capitals' rookie netminder. "We were penalty killing — I think halfway through the game we had 10 penalty minutes or something crazy like that — but your goalie has to be your best penalty killer, and Sammy was tonight."
Samsonov was strong early, helping cover for a handful of defensive mistakes. He started the night with a confident glove save on Alex Killorn, then followed it up with a pad save on Anthony Cirelli. He finished with 26 saves and improved to 8-2-1 with wins in his past three appearances. His eight wins are tied for the most among rookie goaltenders, and his 2.38 goals against average and .918 save percentage rank first.
With the Capitals' on their annual dads trip, Samsonov's father, Aleksei, was on hand, watching his son play an NHL game in person for the first time.
"You know I'm happy because I win this game for him," the goalie said. "His first time watching live my game [in the NHL], it was really important."
With the Capitals' top lines unable to give Samsonov much help early, the team's scrappy fourth line settled things down and opened the door for Washington to capitalize on Tampa Bay's first true mistake of the night — a turnover that Backstrom corralled at the front of the net for the game's first score.
It was the sixth goal of the season for Backstrom, who returned to the lineup three games ago after missing eight contests with an upper-body injury. He has five points (two goals and three assists) since his return. His first game back was Monday's 5-2 loss to Columbus, when he tallied a late goal.
Tampa Bay appeared to have scored an equalizer 4:26 into the second period, but it was quickly waved off after Mathieu Joseph was called for goalie interference.
Barely a minute later, Point's strike off the rush was never in doubt, knotting the score at 1 and snapping a streak of 20 straight penalties killed by the Capitals. Washington became the last team in the NHL to allow a power-play goal in December.
The Capitals were whistled for four minor penalties in the middle frame alone. The Lightning came into Saturday with the second-best power play (29.6 percent) in the league.
"Overall we took too many penalties," Backstrom said. "Tough second period there especially; we had to kill them off there. Other than that, we worked ourselves into the game and we had a good start to the third there, so that was huge and we got two points."
Just after Washington's third minor penalty in the second, Tampa Bay lost Hart Trophy winner Nikita Kucherov after he blocked a hard shot by John Carlson with his right leg and crumpled to the ice. Kucherov was helped to the bench before limping down the tunnel to the dressing room. Kucherov, who has 34 points (10 goals, 24 assists), did not return.
"Just a testament to the guys in the room how hard we came in the third period, and we didn't lose a step, and we played our game," Hathaway said.
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