Center Brad Richardson sat out Friday's short practice after sustaining an upper-body injury in the first period of Thursday's victory over Calgary.
And with his return unlikely before Monday, when the Kings begin a five-game trip in Detroit, the team recalled Oscar Moller from Manchester (N.H.) of the American Hockey League to provide depth on the forward lines.
Coach Terry Murray said he was uncertain how long Richardson would be sidelined.
"I don't know if it's day to day. I don't know how to term that," Murray said. "It's an upper-body injury that we're just going to take our time with and see how he comes around. Hopefully soon."
Moller, 21, has 17 points and 10 penalty minutes in 19 games with Manchester this season. He played in 34 games for the Kings last season, collecting four goals and three assists.
Defenseman Willie Mitchell, who broke his left wrist five weeks ago, is also out until next week at the earliest.
"Sure you're going to play with some pain for a couple of weeks. But it will go away after a while," said Mitchell, who hasn't attempted a slap shot since he was injured. "It's just a matter of getting the right treatment, getting the right rest, doing the right things.
"It will be fine. Just a little inflammation in the joint."
Things got heated in the final moments of Thursday's game when Flames winger Rene Bourque appeared to spear defenesman Drew Doughty with 25 seconds left, nearly touching off a brawl.
"It was just in the stomach, but still, no one likes to get speared," said Doughty, who said he was fine after regaining his breath. "He had no reason to do it. There's a chance the league could fine him, I don't know. I'm sure they'll at least review it."
The Kings made a Christmas wish come true Friday when they invited 6-year-old cancer patient Will McLeod of Valley Village onto the ice after practice.
The boy, who is being treated for acute lymphatic leukemia, had told the Make-A-Wish Foundation he wanted to meet captain Dustin Brown, his favorite player. So for about 25 minutes, Will and his brother Mac, 8, took turns shooting at backup goalie Jonathan Bernier as Brown and winger Kevin Westgarth offered tips.
Will wore a miniature version of Brown's No. 23 jersey while Mac wore center Anze Kopitar's No. 11.
Later, Brown gave the boys a tour of the practice facility, ending in the dressing room where they were presented with gift baskets and a surprise visit from Kopitar, who signed their jerseys.
The boys will also attend Saturday's game against Minnesota.
"It's not too often that you can make a kid's dream come true, so it's definitely something I'm happy to do," said Brown, who spent more than an hour with the boys and their family. "I'm trying to convince Will to get on the Zamboni [Saturday], so we'll see what happens."
Times staff writer Kevin Baxter contributed to this report.