WASHINGTON -- Alexander Semin insists he isn't doing anything differently. The playful smirk on his face after his second hat trick of the season suggested otherwise.

Semin scored three goals during a wild third period and added two assists, Alex Ovechkin had a goal and two assists and the Washington Capitals defeated the Tampa Bay Lightning 6-3 Thursday night for their sixth straight victory.

"It wasn't anything special," Semin said through a translator. "I was just going out there and playing like I do every other game. Most important thing is for the team to win and that's what happened tonight."

That victory, Washington's fifth straight at home, wouldn't have been possible without Semin in the final period. Semin recorded four points in the final 15:27.

With the score tied at 2, Semin converted on a power play with 15:27 left, knuckling a shot from between the circles past Lightning goalie Dan Ellis. With 9:14 remaining, Semin one-timed a pass from Nicklas Backstrom for his team-high 11th goal and a two-goal lead.

After assisting on Ovechkin's ninth of the season with 4:52 left, Semin added an empty-net goal with 16 seconds remaining.

"He's a sniper out there," Backstrom said of Semin. "He can score. I haven't seen Alex play as well as he is right now."

Added Capitals coach Bruce Boudreau: "[Semin] is pretty on right now."

Tom Poti and Mike Knuble also scored for Washington. Backstrom had four assists.

"You're facing guys who have tremendous skill, great accuracy and don't need many opportunities to capitalize," said Tampa Bay coach Guy Boucher.

Steven Stamkos, the NHL's scoring leader, had a goal and an assist for the Lightning. Teddy Purcell and Ryan Malone also scored for Tampa Bay, which has lost three of four.

"We had chances to win the game," Stamkos said. "We didn't bury opportunities. ... They come down and score. That's the way it goes sometimes."

Tampa Bay captain Vincent Lecavalier broke his hand in the first period, returned to play through the second period and finally exited when he couldn't grip his stick without pain. Boucher said Lecavalier, who has three goals and six assists, will miss three to four weeks with a non-displaced fracture.

Boucher doesn't think surgery will be necessary, but he isn't sure. The break occurred on the upper portion of Lecavalier's hand, near the first knuckle of the index finger.

"He played for a long time with it because he didn't want to come off. He's a warrior, this guy. I'm impressed," Boucher said of Lecavalier.

Purcell's goal midway through the first period gave Tampa Bay a 1-0 lead. Purcell skated to the left of the goal when be batted Sean Bergenheim's rebound out of midair and past Michal Neuvirth.

Poti, returning to the Washington lineup after missing eight games with a groin injury, tied it 2:21 into the second period. Left uncovered along the right wing, Poti used a backhand shot to sweep Semin's rebound by Ellis for his first goal of the season.

At 7:51, Knuble put the Capitals ahead with a goal from behind the goal line. When Brooks Laich's shot skittered wide right, Knuble collected the loose puck and tucked it inside the right post.

Tampa Bay tied the game early in the third period after Washington's John Erskine went off for boarding. Malone was at the right post to knock in the rebound of Martin St. Louis' drive from just inside the blue line at 2:43, the Lightning's first power-play goal in five tries.

The tie didn't last long. After Dominic Moore was penalized for hooking Semin, Semin made it 3-2 with a power-play goal, a shot from between the circles that bounced through Ellis at 4:33.

After Semin scored twice, Stamkos got the Lightning within a goal with his league-leading 14th goal, a shot from between the circles off a centering pass. But Ovechkin restored the two-goal cushion, scoring on a delayed penalty call.