Despite taking 45 shots, including 22 during the second period, the Thrashers lost to the Capitals 5-2 in their first game since trading the face of their franchise.
"I thought we played pretty well," Thrashers forward Colby Armstrong said. "I thought we played them pretty tight and had almost 50 shots on net, but we gave up a 2-on-1 and a 3-on-1 in the third period and they scored on both of them."
Kovalchuk went to New Jersey on Thursday along with defenseman Anssi Salmela for defenseman Johnny Oduya, forward Niclas Bergfors, prospect Patrice Cormier and a 2010 first-round pick. The teams also swapped second-round selections in the 2010 Entry Draft.
It was a spirited effort by Atlanta -- turning aside three of four power-play chances in the first period, including a two-man advantage, and outshooting Washington 22-9 in the second -- but a pair of turnovers early in the third cost the Thrashers dearly.
"We didn't have much traffic and many second attempts," Armstrong said. "I think that is probably one of our biggest downfalls. I thought our second period was great, but in the third there for about 10 minutes we tried to go run-and-gun with them and it bit us."
Bergfors took Kovalchuk's place on the team's top line. He had four shots on net in a little less than 13 minutes of ice time. Oduya was paired with Ron Hainsey and finished third among Atlanta's defenseman in playing time.
"I was really happy with them," Atlanta coach John Anderson said. "It was really tough on Oduya because we lost Boris [Valabik] in the first period and we only had five defensemen the whole game. I thought Bergfors played very well with Antropov. We put him on his wrong side and he made some really good plays.
Another wrinkle in the lineup for the Thrashers was the return of Slava Kozlov, who had been a healthy scratch for the past five games. Without Kovlachuk's offensive presence, Anderson inserted Kozlov for Eric Boulton and put him on the second line with Rich Peverley and Maxim Afinogenov.
Kozlov rewarded Anderson's faith with an assist on the team's first goal and tied for the team lead in shots with five. Balance was a key part of Atlanta's attack -- 16 of the team's 18 skaters put shots on net.
Kovalchuk scored 328 goals for the Thrashers, more than double any other player in franchise history. He has the second-most in the NHL since the start of the 2005-06 season behind Washington's Alex Ovechkin.
It was the third straight loss for the Thrashers, but they remain three points out of eighth place for the final playoff spot in the Eastern Conference.
"I think everyone in here still believes we can do it together as a team, which is the most important thing," Armstrong said. "I thought the new guys played well after flying in this morning. I think if we keep playing like that every night with a few adjustments we will have a great effort every night and still be in the hunt."