The Capitals celebrate a second-period goal in Friday’s Game 1. (Jonathan Newton/The Washington Post)

TAMPA — Tampa Bay goalie Andrei Vasilevskiy lay face-down on the ice after the Capitals’ second power-play goal Friday night. Amalie Arena had gone from raucous to near silent. And the Lightning’s struggling penalty kill was a major reason.

Before its 4-2 loss to the Capitals in Game 1 of the Eastern Conference finals, the Lightning had allowed eight goals on 31 power plays in the postseason. Despite its deadline acquisitions of forward J.T. Miller and defenseman Ryan McDonagh, whom Coach Jon Cooper praised before Game 1, the Lightning’s penalty kill remained an issue in the series opener.

“It’s pretty simple,” Lightning defenseman Dan Girardi said on how to combat the Capitals’ power play. “You just got to stay out of the box. Obviously, there is going to be penalties in the game, but one or two you can probably get away with.”

In the Lightning’s second-round series against the Boston Bruins, Tampa Bay allowed five goals on 11 Boston power plays. In the final three games of that series, Boston’s only goals came either shorthanded or on the man advantage.

Tampa Bay’s special teams problems have continued into the its Eastern Conference final series against Washington. The Capitals scored on a pair of power-play chances and finished 2 for 4 with the advantage. Tampa Bay’s weakness plays to a Capitals postseason strength: The Caps lead the NHL this postseason in power-play goals and have scored a power-play goal in 11 of 13 playoff games.

“Our power play struck right away so really gave us some breathing room,” Capitals Coach Barry Trotz said. “I thought the second period we did sort of carry on what we did in the first.”

Washington had five scoring chances on the power play, two each by captain Alex Ovechkin and center Lars Eller and one from forward T.J. Oshie. Tampa Bay only had two blocked shots on the power play.

The Capitals’ first power-play goal came from Ovechkin 19:54 into the first period after Oshie won a faceoff to Evgeny Kuznetsov, who found Ovechkin for a one-timer and a 2-0 lead.

“Obviously the one at the end of the first, it hurts, but it’s a bang-bang play,” Girardi said. “[Ovechkin] has one of the best shots in the league, and [Alex Killorn] tries to block it, and he just shoots it by him.”

The second came 6:42 into the second period when Eller hit a rebound into a wide-open goal to give Washington a 4-0 lead. Ovechkin and Oshie were credited with assists.

“The second one, he fans on it,” Girardi said. “I go to block it, and he fans on it. And everyone thinks it is going to be a hard shot, and it just kind of trickles [to] the net, and they got a tap in.”

Louis Domingue replaced Vasilevskiy in goal for the third period.

Vasilevskiy “did everything he could,” Cooper said. “It was the group ahead of him that didn’t.”

Down 4-0, the Lightning didn’t go away. Steven Stamkos scored on a power play 3:45 into the third period, and Ondrej Palat scored the Lightning’s second goal before time ran out.

“The whole game wasn’t good enough for where we need to be at this time of year,” Lightning defenseman Ryan Callahan said.

And while the Lightning looks for a way to cure its ailing penalty-killing unit, this team is not in unfamiliar territory. Boston beat Tampa Bay, 6-2, in the opener of its second-round series before the Lightning bounced back to win four straight.

“It is just one game,” Cooper said. “That’s the way we have to look at it. We’ve kind of been through this a little bit before.”

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