Washington led 2-1 entering the third period on power-play goals by Mathieu Perrault and Mike Ribeiro.
Andrei Loktionov made it 2-all midway through the last period, and Kovalchuk put New Jersey ahead for the first time off Patrik Elias' assist. Elias had scored a short-handed goal in the second period.
The East-worst Capitals (5-10-1) dropped to 0-7-1 against the conference's top six teams. They will get another chance Saturday when they host New Jersey again.
PANTHERS 5, FLYERS 2
PHILADELPHIA (AP) — Jonathan Huberdeau and Peter Mueller each had two goals to help Florida snap a five-game losing streak with a victory over Philadelphia.
Tomas Kopecky also scored for Florida, which was 0-2-3 since a 3-2 shootout victory in Philadelphia on Feb. 7. Scott Clemmensen, who backs up Jose Theodore, stopped 32 shots to earn his first win since April 7.
Luke Schenn and Jakub Voracek scored Philadelphia's goals in the third period.
The Flyers came out flat one night after a wild 6-5 win at Pittsburgh. It didn't help when they learned before the game that centre Matt Read will miss six weeks because he tore rib cage muscles when hit by the Penguins' Chris Kunitz.
Flyers goalie Ilya Bryzgalov was replaced by Brian Boucher after Florida took a 4-0 lead.
Schenn snapped Clemmensen's shutout bid with 6:08 left.
BRUINS 4, LIGHTNING 2
TAMPA, Fla. (AP) — Nathan Horton scored two goals, and Boston beat Tampa Bay.
Patrice Bergeron and Brad Marchand also scored for Boston, which improved to 6-1-1 on the road.
After blowing a two-goal lead, the Bruins took a 3-2 advantage on Marchand's goal from the slot with 6:02 to go in the second. Horton extended the lead to 4-2 when he redirected Zdeno Chara's pass at 2:33 of the third.
Tampa Bay got goals from Steven Stamkos and Cory Conacher, but the Lightning's two-game winning streak, which followed an 0-5-1 stretch, was snapped.
The Bruins took a 2-0 lead early in the first on goals by Horton and Bergeron. Horton has 26 goals and 46 points in 45 games against the Lightning.
SENATORS 3, RANGERS 2, SO
OTTAWA (AP) — Kaspars Daugavins scored in the seventh round of the shootout and backup goalie Ben Bishop earned the victory in relief of injured starter Craig Anderson as Ottawa beat the New York Rangers.
The Senators lost Anderson at 1:43 of the third period after Rangers forward Chris Kreider was tripped in front and slid into him. No penalty was called on the play and Anderson had to be helped to the dressing room because of a sprained right ankle.
Daugavins appeared to mishit his winning shootout attempt that beat Rangers goalie Henrik Lundqvist between the legs. Kreider was then stopped by Bishop to end the game.
Jakob Silfverberg also scored in the shootout for Ottawa, and Ryan Callahan had the lone goal for the Rangers.
Silfverberg and Mika Zibanejad scored for the Senators in regulation. Anderson stopped all 21 shots he faced before being replaced by Bishop, who allowed two goals on 13 shots.
Callahan and Ryan McDonagh scored 51 seconds apart in the third period for the Rangers. Lundqvist made 35 saves.
BLUE JACKETS 3, RED WINGS 2
DETROIT (AP) — Vinny Prospal scored with 24.7 seconds left, capping a comeback that lifted Columbus over Detroit.
Damien Brunner and Valtteri Filppula scored in the first 2-plus minutes of the game to put the Red Wings ahead by two, a cushion they wasted for a third time during their five-game losing streak.
R.J. Umberger's power-play goal a couple of minutes after Detroit took its two-goal lead pulled Columbus within one. Derek Dorsett tied it in the third period for the Blue Jackets, who snapped a three-game losing streak.
The game took a frightening turn early in the second period when Columbus centre Artem Anisimov was taken off the ice on a stretcher after being struck in the head by Red Wings defenceman Kyle Quincey. Anisimov was alert and able to move when he was taken to a hospital as a precaution.
Detroit scored on its first and third shots against Sergei Bobrovsky, who bounced back to finish with 28 saves.
Jimmy Howard stopped 21 shots for the Red Wings.
MAPLE LEAFS 3, SABRES 1
TORONTO (AP) — James van Riemsdyk scored two goals to lead Toronto past Buffalo, spoiling the NHL head coaching debut of the Sabres' Ron Rolston.
Rolston, who until Wednesday was the head coach of the AHL's Rochester Americans, was hired as the Sabres interim coach following the club's decision to fire Lindy Ruff. Ruff had been behind the club's bench since 1997 and was the NHL's longest-tenured head coach.
The Sabres, who have dropped three straight and five of six, were booed off the ice following Tuesday's loss to Winnipeg.
Van Riemsdyk's power-play goal at 14:28 of the third — his team-leading 11th — gave Toronto breathing room after goalie Ryan Miller stopped him with a glove save earlier in the advantage.
Dion Phaneuf also scored for Toronto, which won its third straight home game. Ben Scrivens stopped 31 shots for his third win in five starts since James Reimer's knee injury Feb. 11.
Tyler Ennis scored for Buffalo.
ISLANDERS 4, CANADIENS 3, OT
MONTREAL (AP) — Rookie defenceman Thomas Hickey scored in overtime for his first NHL goal, and the New York Islanders rallied to snap Montreal's five-game winning streak.
Matt Moulson scored twice and Frans Nielsen added a goal in the third period for the Islanders (7-9-1), who trailed 2-0 and 3-1 but came back to end a two-game slide and win for the third time in 10 games.
Max Pacioretty had two goals, and Travis Moen added one for the Canadiens (11-5-2). After going his first 10 games without a goal, Pacioretty has four in three games.
WILD 3, OILERS 1
EDMONTON, Alberta (AP) — Matt Cullen had two goals and an assist to lift Minnesota over Edmonton.
Devin Setoguchi also scored for Minnesota (8-6-2), which has won two straight. Niklas Backstrom made 25 saves in the victory.
Ryan Smyth had the lone goal for the Oilers (6-7-3), who have lost three of the first four in a five-game homestand that will lead into a nine-game road trip. Devan Dubnyk stopped 25 shots in defeat.
With 2:33 left in the game, Edmonton's Taylor Hall hit Minnesota's Cal Clutterbuck knee-on-knee at centre ice. Hall was given a major penalty for kneeing and was ejected. The play could lead to supplemental discipline for Hall once the NHL reviews it.
Clutterbuck stayed on the ice, writhing in pain, before he was helped to the dressing room.
JETS 4, HURRICANES 3
RALEIGH, N.C. (AP) — Blake Wheeler scored his second goal of the game with 4:54 remaining to lift Winnipeg over Carolina.
Wheeler's goal concluded a stretch in which the teams scored three goals in a span of 1:03.
Jiri Tlutsy scored twice for Carolina, and Jordan Staal also scored for the Hurricanes. Cam Ward made 19 saves.
Andrew Ladd and Evander Kane also scored for Winnipeg, and Ondrej Pavelec made 27 saves. Ladd also had two assists.
The Jets have won the first two games of a five-game trip after losing three in a row at home.
Carolina has lost two in a row after a 5-0-1 run.
Earlier Thursday, Jets rookie defenceman Zach Redmond had surgery to repair a laceration to an artery in his right leg after a teammate accidentally stepped on him during the morning skate.
CANUCKS 4, STARS 3
DALLAS (AP) — Jason Garrison and Henrik Sedin scored third-period goals to help lead Vancouver past Dallas.
Alex Burrows and Kevin Bieksa also scored for the Canucks, who ended a three-game losing streak (0-1-2), including a 4-3 defeat to the Stars in Vancouver on Feb. 15.
Cory Schneider made 22 saves for the win.
Jamie Benn, Michael Ryder and Brenden Morrow scored for Dallas, which lost for the third time in four games.
Cristopher Nilstorp, recalled from AHL Texas on Sunday, stopped 18 shots.