Tomas Fleischmann scored twice during a five-goal third period, and the short-handed Capitals beat the Panthers 7-4 Saturday night for a sweep of their home-and-home series.
Washington played a third straight game without Ovechkin, who has an upper body injury. The Capitals were also without injured defensemen Mike Green and Jeff Schultz, both of whom were hurt Friday night during a 4-1 victory in Florida.
But Washington prevailed anyway, amassing a season-high seven goals in the process.
"Alex is a tough guy to replace, but we've got four lines that can score," said Brooks Laich, who had a goal and an assist.
"If they win this hockey game, it's a split and we look at it as a missed opportunity," Laich said.
The Capitals trailed 3-2 before Perreault scored his first NHL goal with 17:39 to go. Laing then scored his second of the season, and Fleischmann extended his point-scoring streak to a career-high five games with a goal off an excellent pass from Nicklas Backstrom.
Knuble made it 6-4 with 8:54 remaining, and Fleischmann scored again with 6:22 left. Fleischmann has five goals and two assists in six games since being sidelined with a blood clot in his leg.
"Green and Ovie aren't in the lineup. I think that says something: that our other players are good," Capitals coach Bruce Boudreau said. "People seem to forget that."
"It was like Murphy's Law. Anything that could go wrong, went wrong," Clemmensen said. "We weren't very good down low; there were a lot of open guys around the net. It looked like a fire drill down there. It was total chaos from my perspective."
The Capitals repeatedly broke free along the backboards before passing to open teammates in front of the net.
"One thing we need to do is work on our coverage down low and behind the net," Clemmensen said. "I'm not sure how it gets so bad at times. It's a matter of knowing responsibility. Forget about tonight; we're not quite there yet as far as taking care of our own end."
Panthers defenseman Bryan McCabe preferred to give credit to the Capitals.
"They are a very skilled team with or without Alex," he said. "They're one of the best offensive teams in the league, and they showed that tonight."
The Panthers took their first lead at 16:03 of the second period when Kenndal McArdle sent a backhand pass from the backboards to Michal Repik, who beat goalie Jose Theodore with a wrist shot in the slot to make it 3-2.
That capped a three-goal period for Florida -- on only 12 shots.
Washington went up 1-0 in the first period when Knuble scored from the right side of the crease after getting the puck from Brendan Morrison, who weaved behind the net with a pass from Laich.
Early in the second period, Stillman fired a shot that Theodore tipped with his glove before the puck bounced off the left post. Seconds later, however, Michael Frolik jammed in the rebound of a shot by McCabe to make it 1-1.
Laich put the Capitals back in front with a power-play goal at 6:17, but 19-year-old rookie Dmitry Kulikov answered for the Panthers with his first career goal midway through the period.
- Washington has scored first in 14 of 17 games, including each of the last six.
- Frolik had two goals in Florida's first three games, then went 11 straight games without one before his second-period tally.
- The Capitals are 2-1 without Ovechkin this season and 3-4 in the seven games he's missed since joining the team in 2005.