Weiss scored two goals to lead the Panthers to a 5-4 win over the Capitals on Monday night.
The Panthers have a seven-point lead over the Capitals in the Southeast Division, the largest division lead in the NHL.
"When you fess up, the truth is we did look at this as a big game for us," Florida coach Kevin Dineen said. "We looked at it as a test and a team that we aspire to compete with every night. They didn't see our best early in the year (a 3-0 loss at Washington on Oct. 18) and we felt we needed to come out and play a strong game and that was part of the game plan. We certainly did that."
Michal Neuvirth made 25 saves, but struggled in his second start under new coach Dale Hunter.
The Capitals have lost five straight road games and nine of 12 overall.
Trailing 5-2, the Capitals scored two goals in the third period.
The first came on Laich's wrist shot at 12:09 that made it 5-3. Chimera's shot deflected off Clemmensen and into the net at 18:16 to bring the Caps within one goal.
"We got rolling, but we were a little too late," Chimera said.
The Capitals kept the pressure on in the final seconds.
"We battled, we get back in the third, inches away from tying it up," Hunter said. "The boys showed a lot of character that way."
Some Washington players didn't take much solace in the late surge.
"It's not acceptable to play hockey for 20 minutes and not the other 40," Laich said. "You judge yourself by your results, not your intentions. We're not satisfied at all tonight."
Weiss' second goal of the game and 11th of the season came at 12:11 of the second. Tomas Fleischmann passed the puck back to Weiss in the right circle. His wrister went high into the net and gave the Panthers a 5-1 lead.
"Flash said that when he turned and made the pass he was upset because there were three guys in the way and somehow it snuck through and I didn't see it until it was almost on my stick. We'll take it," Weiss said.
Washington made it 5-2 late in the second when Mathieu Perreault passed the puck from behind the net to Eakin in the right circle. His shot beat Clemmensen with 20 seconds left in the period.
The Panthers stretched their lead to 4-1 in the second on a power-play goal by Bergenheim. Bergenheim picked up a loose puck behind the net and his wraparound went in at 3:41.
Florida scored two goals in 13 seconds to take a 2-0 lead in the first period.
Weiss took a shot from the top of the right circle that deflected off a Washington player and past Neuvirth on the glove side at 6:50. Santorelli's wrist shot from low in the right circle got past Neuvirth at 7:03.
The Panthers made it 3-0 on Kulikov's power-play goal. His slap shot from above the right circle beat Neuvirth at 16:31.
The Capitals answered back 40 seconds later when Knuble's shot from the right circle went through the legs of Clemmensen to make it 3-1.
Panthers fans showered the rink with rubber rats at the game's end, a throwback to a tradition started in the mid-1990s when Florida made the Stanley Cup finals.
Notes: Florida G Jose Theodore, set to make his 600th NHL start, was scratched with the flu. Florida recalled Jacob Markstrom from AHL San Antonio. ... The Florida franchise record for fastest goals was 7 seconds on Feb. 10, 2004, when Viktor Kozlov scored two goals against Montreal. ... Washington's Alex Ovechkin took a slap shot off the face late in the second period, but only left the game briefly. ... Washington R Alexander Semin missed his second consecutive game and remains day to day with a shoulder injury. ... Tomas Vokoun, who played four years for the Panthers and signed a one-year contract with Washington in the offseason, did not play in his first return to Florida.