A 3-for-6 effort on the power play helped the Kings spoil Legace's return in his first outing since injuring a hip before a 4-0 loss to the Kings last month. The Blues goalie tripped on a carpet placed on the ice for a ceremonial puck drop by then Republican vice presidential candidate Sarah Palin.
The Kings' attack provided enough of an obstacle for Legace and the Blues.
In addition to the strong showing by their power play, the Kings also generated an even-strength goal by Anze Kopitar and an empty-net tally by Dustin Brown. Kopitar also had two assists, with Brown, Frolov, Preissing and Doughty adding single helpers.
"We had chances, and tonight we really came through," said Kopitar, who scored his first goal in nine games. "I'm personally pretty happy and I'm sure the other guys are pretty happy. Hopefully we can keep on going."
Los Angeles has won consecutive games for just the second time this season. The latest victory came in Ersberg's third consecutive start after Jason LaBarbera was in goal for each of the Kings' first 10 games.
The Kings are 8-5-3 over the past two seasons in games started by Ersberg, including 2-0-1 this season. The 26-year-old Swede dropped a 1-0 overtime decision to the Anaheim Ducks in his first start on Tuesday and then faced 15 shots in a 3-2 victory over the Florida Panthers on Thursday.
"It was a great week, two wins in the last two games and it's fun for me to play games, too," Ersberg said. "When we play like we say we are going to play I think we are a tough team to beat. When we play our system right and everybody is digging in and working hard it's going to be tough to come and beat us here."
Andy McDonald ended the Blues' scoring drought against the Kings that exceeded 101 minutes. He sent in a wrist shot from the slot early in the third period. Patrick Burgland and Brad Boyes also scored for St. Louis.
"I thought we had all kinds of chances to score on our power plays, but Ersberg played well," Blues coach Andy Murray said.
After trailing 4-1, St. Louis drew within a single goal when Boyes scored with 1:26 to play.
"We were trying, we didn't quit," Murray said. "We were battling until the end and I think we made them nervous. They made a good play and got that empty-net goal, but we didn't fade away." Kopitar opened the scoring by wrapping a rebound of Brown's shot past Legace at 3:01 of the first period to make it 1-0.
Then the Kings' power play took over.
Frolov tipped Kyle Quincey's shot past Legace during a Kings advantage 7:14 into the second. Preissing sent a 45-foot slap shot through a screen by Legace with 1:19 to play in the period to make it 3-0.
"We came out of the gate slow and we gave them a three-goal lead, it's tough to come from behind like that," Blues forward Lee Stempniak said. "If we play the way we played in the third all three periods we would have a really good chance of winning our games. We have to get back to basics, make sure were getting the puck in early, making a defensive turn and generating offense."
Doughty scored his second NHL goal in the third period. The 18-year-old rookie defenseman has four points -- including three assists -- in two games.
An MRI on Blues forward Paul Kariya's undisclosed lower body injury didn't reveal further damage. He could return to the St. Louis lineup at Buffalo on Wednesday. ... Kings coach Terry Murray was behind the bench for his 750th NHL game as a head coach.