Capitals defenseman Karl Alzner mixes it up with Tampa Bay’s Steve Downie during the second period at Verizon Center. (Nick Wass/Associated Press)

In Friday’s meeting with the Tampa Bay Lightning, the Washington Capitals seized what appeared to be firm control and dominated the opening 26 minutes or so of play, imposing their will on a struggling divisional foe.

After asserting themselves, though, the Capitals grew dormant offensively and their poise slipped defensively as they allowed Tampa Bay back into the game. Washington weathered two goals by the Lightning in the final 31 / 2 minutes, hanging on for a 4-3 win at Verizon Center.

Led by Troy Brouwer, who recorded his first career hat trick, and a 28-save effort by goaltender Tomas Vokoun, the Capitals (23-17-2) captured their sixth win in the past eight games. The victory gives Washington 48 points and moves it within two of Southeast Division-leading Florida, which lost, 4-1, to Pittsburgh.

“There were a lot of good things in the game, but at the same point at the end of the game there was a lot of uncertainties and mistakes and stuff like that,” Brouwer said. “We’ve got to clean that up, and if we want to beat good teams, like Tampa was tonight . . . we’ve got to clean up our defensive game, clean up our turnovers and just make it so if we are giving up chances that they’re not good, quality chances in tight.”

Things started out extremely well for the Capitals, who are in the midst of a four-game homestand against teams that will all arrive in Washington to play the second of back-to-back games.

Tampa Bay (17-22-4) aided the Capitals’ cause early by taking three penalties in the first 5:07 of the game. Washington didn’t score on the earliest man-advantage, but it wouldn’t let the next two opportunities get away.

Martin St. Louis was in the box for interference when Alex Ovechkin wristed a shot from the point past Roloson, who was screened by Brouwer, to make it 1-0 less than four minutes in.

Shortly after Ovechkin’s tally, Lightning defenseman Eric Brewer cleared the puck over the glass and was whistled for delay of game. It took 38 seconds for that power play to yield a goal, this time a short-side shot by Brouwer that gave Washington a 2-0 lead 5:45 into the game.

At 5:25 of the second period, Brouwer found a juicy rebound in the slot off a shot by Brooks Laich. With Roloson caught to the side, the winger fired into an open cage for his second tally of the night, increasing Washington’s advantage to 3-0. Brouwer hadn’t recorded more than one goal in a contest since Jan. 16, 2011, when he was still a member of the Chicago Blackhawks.

“He’s hard to play against. He’s a tough guy; also, he’s got skill,” Coach Dale Hunter said of the rangy winger. “He’s one of them player combinations that every coach likes.”

After taking the three-goal lead the Capitals began to back off a little, focusing on protecting their lead. The Lightning spent more time in the offensive zone and worked to create havoc, whacking away at stuff attempts near the posts and Vokoun’s skates.

Then Karl Alzner dropped the gloves for the first time in his NHL career — fighting a noted agitator, the Lightning’s Steve Downie — 12:42 into the middle period. The bout wound up offering momentum for Tampa Bay, though, and with just less than three minutes remaining before the intermission Tom Pyatt cracked Vokoun’s shutout bid to make it 3-1.

The Lightning’s goal came during a stretch of just more than 18 minutes bridging the second and third periods and during which Washington failed to record a shot on goal. The team had drifted a little too far trying to safeguard the lead and stopped taking shots on Roloson (16 saves), who has struggled mightily this season.

In the third, as the chippy play between the teams elevated, Steven Stamkos drew Tampa Bay within one with a power-play goal at 16:36. Even after Brouwer added an empty-net goal for his hat trick that made it 4-2 with 59 seconds remaining, the Lightning weren’t done. Vincent Lecavalier scored with 10.2 seconds left in regulation to make it 4-3, a little too close for the Capitals’ liking.

“Probably took the foot off the gas too much,” Alzner said. “I think guys are frustrated that we had that lead 3-1 and a couple penalties and we just couldn’t get any momentum. . . . It is frustrating they scored those goals, but at the same time, you win. So it’s kind of bittersweet.”

Capitals note: Nicklas Backstrom missed a fourth consecutive game with a concussion. The center suffered the injury on Jan. 3 against the Calgary Flames when he was elbowed in the jaw by Rene Bourque.