WASHINGTON -- Nobody thought the Capitals' Matt Niskanen was going to end up with a goal when he started up ice early in the third period Sunday afternoon.

Including Niskanen.

The Washington defenseman went coast-to-coast for the go-ahead goal, left winger Alex Ovechkin notched his 30th of the season, and the Capitals defeated the Philadelphia Flyers 3-2 on Sunday for their third straight win.

"I wanted somebody to come force me to get rid of it because if I hang on to the puck too long I start to get uncomfortable," Niskanen joked. "I haven't scored a goal like that in probably 12 years."

Niskanen skated through center ice, split two Flyers defensemen and banked a shot in off Flyers goalie Steve Mason for his third goal of the season at 5:24 of the period.

"It's like back to the '70's, Bobby Orr and all those guys," Ovechkin said of the goal.

"From start to finish we weren't in the right position unfortunately, from up front to the back end, and it came back to haunt us," Flyers defenseman Michael Del Zotto said of the game-winner.

Philadelphia defenseman Nick Shultz had tied the game with a slap shot from the point 51 seconds into the third.

Defenseman Dmitry Orlov also scored for the Capitals (38-9-4) and Braden Holtby stopped 33 shots for the NHL points leaders, who improved to 29-0-1 when leading after two periods.

Ovechkin joined Mike Gartner (15 seasons) and Wayne Gretzky (13) as the only players to score 30 or more goals in each of their first 11 seasons.

Del Zotto gave the Flyers a 1-0 lead in the first period in game between teams playing the second of back-to-backs, and Mason made 27 saves, but the Flyers failed to cash in on any of their five power-play chances.

"Probably one thing, if we could get a couple more pucks on net," Flyers head coach Dave Hakstol said. "I think we had some opportunities that instead of getting the puck on net, we missed a few, especially on top ... we couldn't get one to go."

Philadelphia (23-19-9) did have the services of top goal scorer Wayne Simmonds, who was not suspended by the NHL after being ejected from Saturday's loss to the Rangers for punching Ryan McDonagh.

The Flyers came up empty on a pair of power-play chances during the first five minutes of the game but took a 1-0 lead with 1:39 left in the first period when Del Zotto's blast from the point eluded Holtby.

Holtby was sharp when the Flyers had several chances, but failed to cash in during a 53-seoncd 5-on-3 advantage midway through the second.

The Capitals had allowed goals in five of 16 power plays over five games before shutting the Flyers down on Sunday.

"We need to bear down a little bit more. Better on our pressure moments and better on our clears. Pucks have just been sneaking through," Washington defenseman Karl Alzner said. "I think (today) we were way better on our pressure moments in some of the kills."

Ovechkin got the equalizer with 4:04 left before intermission when he deflected a shot by defenseman Karl Alzner past Mason from the slot.

Just 59 seconds later, Orlov made it 2-1 when he skated around a defender into the left circle and fired high to the far side of Mason.

NOTES: LW Andre Burakovsky became the eighth Washington player to reach the 10-goal mark on Saturday. No other team has as many players with 10 or more goals. ... Flyers D Shayne Gostisbehere came in with a seven-game scoring streak (two goals, eight assists), a new record franchise record for a rookie defenseman. ... Capitals LW Marcus Johansson (upper body) missed his fifth game, and D Connor Carrick and RW Stanislav Galiev were also scratched. ... Philadelphia scratches were C Jordan Weal, C R.J. Umberger and D Brandon Manning. ... The season series concludes March 30 in Philadelphia.