Tomas Fleischmann had a goal and an assist and Washington beat Atlanta 4-2 on Tuesday night for the Capitals' second win over the Thrashers in three days. Washington took a 6-4 home win over Atlanta on Sunday.
Simeon Varlamov stopped 29 shots in only his fifth start of the season for Washington, which moved four points ahead of New Jersey in the conference with the Devils' 4-1 loss to Toronto.
The Capitals weren't content despite winning their first of three straight road games to close the regular season.
"We had lots of turnovers," said Alex Ovechkin, who had two assists. "We didn't have lots of emotion or lots of energy."
Sergei Fedorov, who was set up by Ovechkin on a third-period goal that helped put the game away, said he was "not very happy with my performance."
"I wasn't really feeling it with my linemates, so we'll have to regroup and come back with a fresh attitude and try to put the pieces together," Fedorov said.
Washington scored three first-period goals and led 3-2 midway through the third period when Fedorov jammed in a rebound after Atlanta goaltender Ondrej Pavelec stopped a shot by Ovechkin.
Viktor Kozlov and Alexander Semin also scored for Washington.
Rich Peverley and Marty Reasoner scored for Atlanta.
The Capitals stopped the Thrashers on each of six power plays, but Washington coach Bruce Boudreau wasn't happy with the penalties.
"When you run into all these penalties, you take three in the second and three in the third and that leaves you with only 14 minutes (at full strength)," Boudreau said. "... We've got to find a way to stay out of penalty box.
"It was an ugly win, but it's OK."
After Fleischmann's goal gave the Capitals a 1-0 lead, the Thrashers tied the game when Peverley scored midway through the opening period.
Kozlov answered for Washington about 30 seconds later as Pavelec moved up the slot, leaving himself out of position to stop the shot.
Semin gave Washington a 3-1 lead late in the period. After the Thrashers mishandled the puck at center ice, Semin found the net when Pavelec lunged forward, again leaving himself out of position.
"In the first period we were playing pond hockey with one of the most talented teams in the National Hockey League," said Atlanta coach John Anderson.
Reasoner tipped in an attempt by Tobias Enstrom only 1:05 into the second period, cutting Washington's lead to 3-2.
After his rocky opening period, Pavelec recovered to allow only one goal the rest of the game. He stopped 22 shots.
"After the first period, I put it behind me and focused for the next period to win that period," Pavelec said. "After the first, we played good hockey."
Anderson said he was "very happy" with Pavelec's finish.
"We left him alone in the first period a little bit," Anderson said. "Other than that, I thought he got stronger as the game went along."
Varlamov improved to 4-0-1 in five starts.
"I thought he played really, really good," Boudreau said.
Added Fedorov: "He saved us."
The Capitals won four of six games in the season series between the Southeast Division rivals. ... Atlanta had no penalties in the first two periods and only one in the game. ... Ovechkin, who had two assists, began the night two points behind Pittsburgh's Evgeni Malkin for the league scoring lead. ... Pavelec, making his first appearance since Dec. 18, was recalled from Chicago of the AHL on Sunday.