Alexander Semin records the game-winner 13 minutes 27 seconds into the third period when his shot from near the right wall went off the stick of Panthers’ forward Sean Bergenheim and past former Capitals goaltender Jose Theodore. (Alan Diaz/Associated Press)

Kicking off a four-game trip critical to their playoff hopes, the Washington Capitals understood they could ill afford to lose Friday night’s meeting with the Florida Panthers.

So despite a disallowed goal, part of an opening 44 minutes in which they failed to score, the Capitals showed their determination to not leave South Florida without a pair of important points. Washington fought back from a one-goal deficit to capture a 2-1 win on third-period tallies by Alex Ovechkin and Alexander Semin.

Although they remain in ninth place in the Eastern Conference standings, the win pushed the Capitals (29-23-5) to 63 points, only two behind Southeast Division-leading Florida and one out of a playoff spot.

“Everybody play with fire,” Ovechkin said. “I think because it’s playoff hockey right now for us — you can’t lose it.”

The Capitals outshot Florida, 41-23, and at times controlled play, but through the first two periods it didn’t seem as though they could get a break to go their way.

Panthers netminder Jose Theodore, who finished with 39 saves, withstood early chances with aplomb in his first appearance against Washington since he left the team following the 2009-10 season. His play allowed Florida to play it safe against the Capitals and nurse a one-goal lead, taken on a defensive miscue that led to a one-timer by former Washington forward Tomas Fleischmann with 39.8 seconds left in the first period.

Fleischmann’s goal was the first by the Panthers against Tomas Vokoun (23 saves) in three meetings this season against his former team. Friday’s game was the veteran goaltender’s first at BankAtlantic Center since he left the Panthers (27-19-11) for the Capitals as a free agent this past offseason.

Theodore turned away open looks by Troy Brouwer in the slot and a sublime chance for Semin on a power play, and he routinely dismissed chances by the Capitals’ most effective line of the night — the fourth unit of Jay Beagle, Jeff Halpern and Joel Ward, who created multiple chances and accounted for four shots.

“The goalie was good tonight and we just kept getting more pressure and more pressure, just [kept] getting pucks to the net,” Coach Dale Hunter said. “The guys did a good job of getting traffic in front of there and we got rewarded for it.”

It appeared the reward finally came with 44.6 seconds remaining in the second period, but the would-be tying goal was disallowed.

Mike Knuble, playing in his first game after being a healthy scratch for three straight, planted himself in his customary spot in front of the opposing net. He tipped Brooks Laich’s shot from the left wing past Theodore and into the net. Referee Eric Furlatt waved the goal off immediately, however, and called a goaltender interference penalty on Knuble. The Capitals would enter the third period trailing, 1-0.

“There’s no doubt it’s frustrating, but at the same time, you’ve got to try and say to yourself: ‘You know what? You’re in the right spot.’ You get those old feelings back that you’re in the right spot and where you’re supposed to be,” said Knuble, who added that the call appeared to spark the Capitals. “I think it makes guys angry. Made guys a little bit angry after the [second period] that we’re working hard and just stay with what we’re doing and they still took one away from us.”

It was a questionable call and a worse break for the Capitals, but they didn’t allow that frustration to show on the ice. Less than five minutes into the final period, Washington overloaded the crease and slot with traffic on the power play and the puck found its way to Ovechkin, who rifled it past Theodore to make it 1-1.

Ovechkin’s goal at 4 minutes 47 seconds provided the energy the Capitals needed for another push to close out the contest. Semin recorded the game-winner 13:27 into the third when his shot from near the right wall went off the stick of Panthers forward Sean Bergenheim and past Theodore.

From there, the Capitals turned their focus to smothering the rest of the time off the clock, gaining a valuable two points and setting a positive tone to start this trip, which continues Saturday against the Tampa Bay Lightning.

“It felt like a playoff game where there’s a huge amount of desperation and frustration in the room,” forward Jeff Halpern said. “To get rewarded I thought was big. We have 20-something games left; it’s just one game. We’ve dug ourselves in a little bit of a hole we have to get out of. It helps to win at least one.”