WASHINGTON - Alex Ovechkin’s record-setting goal in the first period wasn’t enough to calm the nerves of the Washington Capitals, whose march toward the playoffs was being threatened by a nothing-to-play-for last place team.

His third-period blast that gave the Capitals the lead? Now, that did the trick.

Serenaded again with chants of “M-V-P!” from the red-clad sellout crowd, Ovechkin scored his 64th and 65th goals Thursday night, breaking Luc Robitaille’s single-season NHL mark for left wings and leading the Capitals to a 4-1 victory over the Tampa Bay Lightning.

“As a whole, we were a little nervous,” Washington coach Bruce Boudreau said. “It’s getting down to the nitty-gritty, you know.”

The win put the Capitals into the top eight in the Eastern Conference, although they have only one game left to play while Boston and Philadelphia still have two to go. Washington likely needs to beat Florida at home in Saturday’s regular-season finale to reach the postseason for the first time since 2003 — and for the first time in Ovechkin’s young career.

“It’s a good time for us right now,” Ovechkin said. “We have a chance, and we have to keep it going.”

The 22-year-old Russian tied the game — and passed Robitaille — in the first period after the Lightning stunned the crowd with a goal in the first minute. The score remained an all-too-antsy 1-1 until Ovechkin’s power-play drive from the top of the left circle with 12:10 left in the game.

It was Ovechkin’s 22nd power-play goal of the season, tying Peter Bondra’s team record.

“He really turns it up when the game’s on the line,” Washington center Brooks Laich said.

The Capitals have won six in a row — their longest winning streak since Jan. 8-19, 2000 — and 10 of 11. They also notched their 17th comeback victory under Boudreau, who took over a last-place team when Glen Hanlon was fired in November.

Boyd Gordon and Tom Poti added insurance goals late in the third period, and Cristobal Huet made 18 saves for his eighth straight win, the longest streak for a Capitals goalie since Pete Peeters won nine in a row from Jan. 28 to March 3, 1987. Huet is 10-2 since he was acquired from Montreal at the trade deadline.

The Lightning, playing out the string in last place, dropped their third straight overall and fifth in a row on the road. They lost leading scorer Vincent Lecavalier with 13:15 remaining in the game when he hurt his shoulder falling awkwardly after a hit by Washington’s Matt Cooke.

Lecavalier will have an MRI on Friday and will miss Saturday’s regular-season finale at Atlanta.

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“It’s an absolute cheap shot,” Tampa Bay coach John Tortorella said. “We have stick fouls — stick foul after stick foul — and then I see that. It’s a guy in a vulnerable position. It’s an interference if the puck isn’t anywhere near him, and that isn’t called. It’s an absolute cheap shot.”

For the Capitals, the evening had the trappings of a letdown game, coming two days after a high-energy victory over division leader Carolina. Sure enough, the Lightning needed only 39 seconds to take the lead, with Filip Kuba flipping in the puck after Huet was unable to control a rebound.

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The Capitals thought they had tied the score less than 90 seconds later when Brooks Laich put in a rebound, but the goal was disallowed in an unusual case of secondhand goaltender interference. Washington’s Tomas Fleischmann pushed defenseman Matt Smaby into goalie Karri Ramo, who had come well outside of the crease.

Ovechkin evened the score for real when Viktor Kozlov drove to the crease on a 2-on-2 break. The puck came loose and deflected off defenseman Alexandre Picard’s skate and into the net. Kozlov was initially credited with the score before replays showed Ovechkin got his stick on it before it hit the skate.

Washington outshot Tampa Bay 40-19.

Notes: Robitaille had 63 goals with Los Angeles in the 1992-93 season. ... Bondra’s 22 power-play goals for the Capitals came in the 2000-01 season. ... The Capitals played without D Shaone Morrisonn (upper body injury). ... Washington has won five straight at Verizon Center, outscoring the opposition 16-6.