"With that (power play) goal just coming on the heels of them scoring the (go-ahead) goal, I think that all of a sudden it was like the wind went out of our sails and we weren't going to get that comeback that we've had for (six) games in a row," Ducks coach Bruce Boudreau said. "They played good, but we could have played much better."
Brown had a chance to extend the Kings' lead with 2:33 to play on a penalty shot. He was on a breakaway when he got pulled down from behind by Ben Lovejoy. But Fasth forced Brown wide right and he missed, making him 1 for 3 on such shots in his career.
Jeff Carter made up for it by scoring with 20 seconds left.
The Kings twice rallied from one-goal deficits in the second to tie the game.
Brown made it 2-2 on his shot from center ice that sailed over Fasth's head, hit the crossbar and bounced in at 17:53.
Penner tied it 1-1 on a tip-in off a pinpoint pass from Jarret Stoll at 3:16. Stoll also earned his 200th career assist. It was Penner's first goal since scoring the game-winner in overtime of Game 5 in the Western Conference finals last year.
The Ducks led 1-0 on Andrew Cogliano's goal off a rebound that got under Fasth's glove 13 seconds into the second. They took a 2-1 lead on Koivu's power-play goal at 5:51. Rob Scuderi swept away a rebound in front of the net that went to Koivu, who scored his fifth goal.
The Kings outshot the Ducks 10-7 in a scoreless first.
Notes: The Kings have beaten the Ducks four straight at Staples Center. ... The Ducks won the first meeting 7-4 in Anaheim on Feb. 2. ... Ducks RW Teemu Selanne played in his 100th career game against the Kings. He is Anaheim's career scoring leader against them with 52 goals and 66 assists. ... Penner played in his 499th career NHL game. ... The teams will meet twice more in April.