In a crowd in front of the crease, Backstrom looked as if he were wearing the wrong-colored jersey when he got his stick on a rebound and backhanded it past goalie Cristobal Huet.
Backstrom, who wasn't available for comment after the game, was either hoping to push the puck gently to Huet or forcefully clear it to the side of the net.
Either way, he failed, and the goal was credited as an unassisted score for Crosby, who took the original shot. The puck was close to striking Crosby's skate on the way into the net, but the Penguins star said he thought it went in clean off Backstrom's stick.
"We've been on the other side of that before. Obviously, it's not fun," Crosby said. "It's a big break for us."
The goal was Crosby's second of the game, his first goals since returning last week after missing 21 games with a severely sprained ankle. Jordan Staal added an empty-net goal with 12 seconds remaining, and Petr Sykora also scored for the Penguins, who moved within one point of first-place New Jersey in the Atlantic Division.
Evgeni Malkin had three assists to give him 92 points, gaining ground on Ovechkin in the NHL scoring race. Ovechkin (two assists) has 95 points.
The win also gave Crosby another notch in a one-sided head-to-head rivalry with Ovechkin. The Penguins are 10-1 against the Capitals when both are playing.
"I'm not where I want to be," said Crosby, who has 22 goals this season. "But I'm getting a better feel for things. The first couple of games, conditioning-wise, I wasn't there."
Coach Michel Therrien said he had a talk with Crosby before the game to discuss "little things to help him to get his game better."
"There's no athlete that could come back to competition after such a long time being out of the game," Therrien said. "There's no doubt tonight that was the best performance I've seen since he's been back."
Brooks Laich and Alexander Semin scored for the Capitals, who have lost back-to-back games in regulation for the first time since coach Bruce Boudreau was hired on Thanksgiving Day. Washington blew a late one-goal lead to lose 2-1 at Boston on Saturday and remains seven points behind first-place Carolina in the Southeast Division, prompting Boudreau to say his team will have to "hope a little bit" to get to the playoffs.
"That was officially heartbreaking," Boudreau said. "I feel bad for Nick. He was doing everything that he could and ends up shooting it in his own net."
After a scoreless first period, Laich redirected Semin's slap shot on a power play for the first goal. Sykora tied the game with his 22nd goal less than a minute later after a pair of quick passes from Malkin and Jeff Taffe on an odd-man rush, with Sykora able to get off the shot even though Laich had put a stick on the puck.
Crosby then put a rebound under Huet's pad to make the score 2-1.
Washington tied the game in the final minute of the second period on a 5-on-3 power play. Having allowed a pair of late 5-on-3 goals in the loss at Boston, the Capitals capitalized on the two-man advantage by passing the puck around to Semin for his 21st goal.
The Capitals outshot the Penguins 33-13 in the first two periods, but Pittsburgh tested Huet often in the third. The goalie had to stretch his left leg as far it could go to stop Staal's shot, and Sergei Gonchar hit the post.
- The Capitals went 48 games without losing consecutive games in regulation under Boudreau. Every other team had at least two sets of consecutive regulation losses during that stretch.
- The Capitals didn't allow a first-period goal for the eighth straight game.
- Pittsburgh RW Marian Hossa missed his sixth straight game with a sprained right knee.