Theodore made 19 saves Tuesday night in earning his second shutout of the season and lifted the Capitals to a 3-0 win over the slumping Panthers, who didn't manage a shot in the third period.
"No shots in the third period," Theodore said, "that's a first for me."
"I thought the defense as a whole played as good as I've seen them play all year," Washington coach Bruce Boudreau said. "To hold them to zero shots in the third period and 19 in their building in a game that they had to win was quite a testament."
Florida dropped a fourth straight game for the first time since late December. The Panthers hadn't lost two consecutive home games since January.
"Tonight was the first night I've been really disappointed with how we've played," Florida coach Pete DeBoer said. "There's been very few nights this year where I've questioned our effort level. They haven't always been pretty and we haven't always won but usually we've brought a good desperation level, and the effort's always been there. Tonight, it was questionable."
Washington remained in third place in the Eastern Conference behind the New Jersey Devils, who beat the Chicago Blackhawks 3-2. The Capitals had an opportunity to move into second place on Monday but lost 5-1 to the Atlanta Thrashers in Washington's most lopsided defeat since a 6-2 loss to Florida on March 1.
Tomas Vokoun stopped 22 shots for Florida, which is in the midst of a five-game homestand.
Vokoun had lost two previous starts against Washington this season and is 1-6 in his last seven games against the Capitals.
"They played their third game in four nights. We didn't take advantage of that," Vokoun said. "It's tough. We need to get our power play going and get some kind of spark and it's crucial this time of year."
The Panthers went 8-5 in February but the team, coming off a 4-3 shootout loss to the Tampa Bay Lightning on Saturday, has been struggling of late. Florida, which has not been to the playoffs since 2000, entered Tuesday's game in ninth place in the East. The Panthers are one point behind eighth-place Carolina.
"If you can't look at the standings and create that desperation now, I don't know how you create it," DeBoer said. "We know where we're sitting and the fight we're in. That should be self-manufactured this time of year. You're not going to create that if they can't create it themselves."
Kozlov's goal made it 2-0 at 2:36 of the third period, beating Vokoun with a wrist shot from the top of the left circle. The Capitals took a 1-0 lead with Laich's short-handed goal at 5:46 in the second period. Laich's wrist shot from a sharp angle found the back of the net for his 18th goal.
"I threw the puck at the net," Laich said. "I watched the replay and he was a little outside the crease, maybe he played the angle a little bit too much. It's a lucky goal, but you throw the puck at the net, you never know what happens."
Alex Ovechkin, held without a point for the first time in 11 games on Monday, had an assist on Green's goal, but it was the first time in a month that he has had back-to-back games without netting a goal.
Panthers defenseman Bryan McCabe, who had missed three straight games with a fractured orbital bone, returned to the lineup. ... Washington is 4-0 when playing on the road on St. Patrick's Day. ... Vokoun was honored for his 500th NHL game, which was March 7 against the St. Louis Blues.