By Annie Ross

All of a sudden, the Washington Caps are playing confidently.

As befits a team that has made the NHL Final Four for the first time in 20 years.

Putting an emotional second-round victory over playoff nemesis and two-time defending Stanley Cup champion Pittsburgh behind them, the visiting Caps got a power-play goal and assist from Alex Ovechkin in his Eastern Conference finals debut and beat the Tampa Bay Lightning 4-2.

Braden Holtby stopped 19 shots and Michal Kempny, Jay Beagle and Lars Eller also scored for the Caps, who are alive beyond the second round of the playoffs for the first time in Ovechkin’s brilliant 13-year career.

“We had a really good start. We didn’t give them much,” Ovechkin said.

“I think it’s we realized we just have to play our way,” the Washington captain added. “It doesn’t matter which position we are, which round it is. Everybody was paying the price.”

Steven Stamkos and Ondrej Palat scored for Tampa Bay, which trailed 4-0 heading into the third period.

Game 2 is Sunday night at Amalie Arena, where Tampa Bay also lost Game 1 in the second round against Boston.

“It’s just one game. That’s the way we have to look at it,” Lightning coach Jon Cooper said. “We’ve got to get back to what got us to the conference final.”

The Capitals dominated in improving to 6-1 on the road this postseason, with Kempny giving them an early 1-0 lead.

Ovechkin made it 2-0 a mere 5 seconds after the Lightning thought they had tied it in the closing seconds of the opening period. But Nikita Kucherov’s would-be breakaway goal was waved off because Tampa Bay had too many men on the ice.

T.J. Oshie won the ensuing faceoff in the Lightning zone, getting the puck to Evgeny Kuznetsov, who fed Ovechkin for the Washington superstar’s ninth goal this postseason – 55th overall in 110 career playoff games – at 19:54 of the first.

“That gave us a real boost … gave us some breathing room,” Capitals coach Barry Trotz said.

Beagle and Eller scored in the first seven minutes of the second period for a 4-0 lead. Up to that point, the Lightning – the NHL’s highest-scoring team during the regular season – had allowed as many goals as they had shots.

Tampa Bay replaced goaltender Andrei Vasilevskiy with Louis Domingue after the starter allowed four goals on 25 shots through two periods.