With four losses in six games, the New Jersey Devils have fallen out of the Eastern Conference lead.
The Ottawa Senators' stellar play in their last six, meanwhile, has them climbing fast in the standings.
The Senators try to win a seventh straight game for the first time since 2007 on Tuesday night, but to do so they'll have to beat the Devils for the first time in two years.
New Jersey was held to 11 goals in going 2-4 over its past six contests. That slump, combined with Washington's surge, has dropped the Devils from four points up on the Capitals atop the East to three points behind them.
Ottawa (28-21-4) also appeared to be fading this month, losing five in a row from Jan. 5-12 to drop into a tie for eighth.
The Senators, though, are getting healthy and making a move. Daniel Alfredsson came back one game into the team's six-game winning streak, and Jason Spezza returned Sunday at Boston after a 20-game absence.
Both scored in a 2-1 victory over the Bruins.
"I knew the guys were playing well, we went through a real tough stretch and we kind of got things together a bit so I wanted to play well," Spezza said after recording his sixth goal of the season.
The hot streak has lifted Ottawa into fifth place in the conference.
Alfredsson has five goals and four assists since returning, but goaltending has keyed the turnaround. Brian Elliott started the last four games and posted a 1.25 goals-against average for the Senators, who have outscored opponents 20-7 during the six-game run.
"I think we obviously got some key players back and our system is being executed very well," Elliott said. "I think teams are having trouble with that."
One team that hasn't had trouble with Ottawa in recent years is New Jersey (34-15-1), which should provide a major challenge as the Senators try to win seven in a row for the first time since an eight-game run from Oct. 13-Nov. 6, 2007.
The Devils have outscored Ottawa 31-16 in winning nine consecutive meetings. The Senators' last victory in the series came during its eight-game streak, 4-1 at home Oct. 27, 2007.
Martin Brodeur started six of those wins, posting a 1.80 GAA, and he was in net for all three New Jersey victories over Ottawa this season.
Jamie Langenbrunner has two goals and three assists against the Senators in 2009-10, and he helped the Devils to a much-needed win Saturday. He opened the scoring 5:52 in and assisted on two Zach Parise goals in a 4-2 victory over the New York Islanders.
Parise's first goal, which tied the score late in the second period, snapped his team's nine-game, 0-for-23 slide on the power play.
"It was a relief because we've been working hard on the power play to get goals," coach Jacques Lemaire said. "The guys were really happy we got it. You could feel it on the bench."
The Devils are 20-5-0 when they score with the man advantage.
Ottawa has finally started to produce on the power play, going 5 for 16 in its past four games following a 2-for-52 stretch that began the game after Spezza was injured. The Senators' 15.3 percent conversion rate is still the league's worst.