PITTSBURGH --The Washington Capitals steamroll into Pittsburgh with a nine-game winning streak in tow but without a chip on their shoulder.

"Just playing to our potential, I think," Capitals defenseman Matt Niskanen said after he scored twice Sunday in a 5-0 win over Philadelphia. "We feel like we can be a really good team when we play a certain way and have a good shot to win every single night. Guys have been bringing it. It's been fun."

The Capitals (29-9-5) moved into first place in the NHL heading into their game Monday against the rival Penguins at PPG Paints Arena.

Washington has a 40-11 goals edge during its streak, including four shutouts in its past six games. It has not allowed an even-strength goal since Jan. 3 against Toronto, a stretch of 369 minutes, 14 seconds.

"I think we're just a little more aggressive," Nicklas Backstrom said of the Capitals' strong five-on-five play. "We're making plays in the offensive zone. But at the same time, we're good at managing the puck in the neutral zone."

One of Washington's wins during its streak was a 5-2 job against visiting Pittsburgh on Wednesday. No. 1 goaltender Braden Holtby made several strong saves in that game, and while Philipp Grubauer picked up the shutout Sunday, Holtby is expected to start Monday against the Penguins.

Holtby this season is 2-0-1 in three starts against Pittsburgh with 1.62 goals-against average and a .943 save percentage. During the winning streak, he has three shutouts.

"He looks big out there," teammate Justin Williams told the Washington Post. "It doesn't seem like there are any holes in him. He's controlling rebounds. He's just composed."

Pittsburgh (26-11-5) has lost three games in a row, beginning with Wednesday's game at Washington, after not having lost back-to-back regulation games since mid-December 2015. The losing streak came on a three-game road trip.

While the Penguins have struggled on the road, dropping to 8-9-3, they have the league's best home record, 18-2-2.

Evgeni Malkin somewhat boldly predicted Pittsburgh would even things up in its three games this week, beginning with the game against the Capitals.

"Of course, we're not happy. We lost the three games," he said. "I believe we'll (bounce) back. These next three games, we should win. If we want to be a good team, make the playoffs, we need to start with the next game against Washington. We play at home. Just play right."

Pittsburgh has been outscored 15-6 during its three-game slide. Sidney Crosby said the team has hurt itself by helping opponents.

"There are sometimes when you can kind of get away with making mistakes, and sometimes it goes like this, were every mistake, it feels like it's a big one and a really good chance (for the opponent)," he said. "So, when that happens, you've just got to tighten up. Those details are even more important when it's going like this so you've just got to bear down all over the ice."

Penguins top defenseman Kris Letang left Saturday's 6-3 loss at Detroit with what appeared to be a left leg or knee issue. The team was off Sunday and there was no update on his status or his availability for the game against Washington.