John Carlson had two assists, getting the 300th of his NHL career when he set up Ovechkin's one-timer from the left face-off circle to make it 1-0 at 11:48 of the first period. Ovechkin and Carlson passed back and forth to get Campbell off balance, with Ovechkin scoring on the second return pass.
"I think [Carlson] does a great job of not really letting anyone know when he's going to give it to [Ovechkin]," Washington forward Brett Connolly said. "He's not looking at him half the time anyways. [Ovechkin] just needs a little bit of room like we all know, and if there's a little bit of traffic in front and the goalie is kind of looking around, it's tough for goalies to get back, especially when he puts it where he wants it."
Connolly scored 20 seconds after Ovechkin to give Washington a 2-0 lead at 12:08 of the first when he tipped Andre Burakovsky's shot.
Ovechkin made it 3-0 at 5:27 of the second period with another one-timer from the left circle off a pass from Carlson for his NHL-leading 42nd goal.
"It's really hard to read, and there's obviously quite a bit of power behind it, so, yeah, it's a special shot, for sure," said Pheonix Copley, who made 26 saves to win his third straight start.
It was the 13th power-play goal for Ovechkin, who has at least 13 goals on the man-advantage in 13 of his 14 NHL seasons.
Each of Ovechkin's four goals during his streak has come on a one-timer from the left circle.
"The puck can move a heck of a lot faster than a player," Carlson said. "It's just constantly kind of a chess game and finding what's open, but regardless, we want to get him the puck, and I think everyone knows that."
Iafallo got to the far post to tap in Brown's pass at 8:20 of the third period and cut it to 3-1.
Kovalchuk made it 3-2 at 19:32 on a slap shot from the blue line with Campbell off for the extra attacker.
"Yeah, we sat back a little bit in the third, but we closed it down," Connolly said. "It's not easy to win on the road, and we found a way to win after not playing our best last night. Got a little nerve-wracking at the end, but we found a way."