"It was great to see," Zajac said. "We did a good job of shooting the puck and crashing the net. All three goals were on good shots. We haven't been playing our best the last couple of weeks, and we wanted to get back to it. Tonight we controlled a lot of the play and protected the puck. That's what we're good at."
Devils backup goalie Kevin Weekes made 34 saves in his first start since a 4-2 loss against Buffalo on Dec. 13. Jamie Langenbrunner had a goal and an assist, first-time All-Star Zach Parise got his 100th career goal and Zajac had two assists. Both of them were as a result of faceoffs he won against Michal Handzus deep in the Kings' zone, leading to New Jersey's first two goals.
The only other time this season that the Devils had three power-play goals was Dec. 19 in a 5-1 win over Ottawa.
"We made it real simple tonight," Langenbrunner said. "We shot it quickly and didn't waste time trying to set up the perfect play. We got the puck to the net. We needed to get it turned around, and tonight was definitely a big step in that direction.
The power play came up big and scored a few goals, and we played a pretty solid game."
Weekes lost his shutout bid with 18:43 remaining when Derek Armstrong redirected Alexander Frolov's shot from the top of the right circle. Armstrong returned to the lineup for the first time since Dec. 9 after missing 13 games, the last seven with a concussion.
Scott Clemmensen started the previous 13 games for New Jersey and 24 of 27 after Martin Brodeur went down with a torn biceps tendon that required surgery and will sideline him for at least another month. Clemmensen was pulled from Thursday's 4-0 home loss against Atlanta after giving up three goals on 19 shots through two periods.
"It's always tough when you don't play a lot, especially having been a No. 1 goalie before. But this is my role," said Weekes, who played a career-high 66 games in 2003-04 with Carolina.
The Devils opened the scoring at 14:02 of the first, only 4 seconds after Matt Greene was sent off for tripping Langenbrunner.
Zajac got the draw back to Elias and he made a cross-ice pass to Langenbrunner, whose long slap shot glanced off Zajac's stick and past Jonathan Quick's glove as the Devils' center skated in front of the crease.
"Too many undisciplined penalties," Kings coach Terry Murray said. "It was the same as the last game against Anaheim."
New Jersey's second goal came at 1:07 of the second - again just 4 seconds after Sean O'Donnell was sent off for hooking Elias.
Zajac got the draw right back to Elias, whose slap shot from the right point was good for his 19th goal.
"We won some big faceoffs tonight at some pretty key times," Langenbrunner said. "When you go on the power play and start it with possession, it's definitely to your advantage."
Parise made it 3-0 just 71 seconds later, scoring his team-leading 23rd goal of the season on a short backhander over Quick's glove after Elias forced Greene to cough up the puck to Parise about 15 feet inside the Kings' blueline. Parise's 100th goal came in his 284th game. His father, J.P. Parise, had 89 goals through his first 288 games and finished his 14-year NHL career with 238 in 890 games.
Rolston, playing in his 1,000th NHL regular-season game, increased New Jersey's lead to 4-1 on a slap shot from the left point with 13:31 left in the game and 6 seconds remaining on an interference penalty against Raitis Ivanans. Langenbrunner completed the scoring with 9:02 left.
Rolston made his NHL debut on Feb. 5, 1995 with the Devils against Pittsburgh, playing on a line with Corey Millen and current Devils assistant coach John MacLean.
"At that point, you're just trying to get to your second game in the league," Rolston said. "It's been a long journey. I've been fortunate to have played for some good teams along the way and be around as long as I have. It was a special night, and now we move forward to the next 1,000."
Earlier Saturday, the Devils agreed in principle on a contract with unrestricted free agent Brendan Shanahan, who hasn't played since finishing last season on the other side of the Hudson River with the New York Rangers - and helping them knock New Jersey out of the playoffs in the first round. Shanahan turns 40 on Jan. 23.
Shanahan, an eight-time All-Star with 650 goals, spent his first four NHL seasons with the Devils after they made him the second overall pick in the 1987 draft. New Jersey won three Stanley Cup titles after he left the club to sign a free-agent contract with St. Louis in 1991, but Shanahan eventually won three Stanley Cup rings with Detroit.
"You try to find ways to make your team better, and we were able to do that today," coach Brent Sutter said. "We're bringing in an experienced player who knows how to win, and he can still play the game."