A scoring drought was behind the Kings' recent slump, with Smyth's injury absence directly correlating to a decline in the formerly potent offense - particularly for Kopitar, the NHL scoring leader when his linemate went down with an upper body injury.
"The other teams are going to focus on you and try to take space and time away, but your teammates can come through in that situation," Kopitar said. "That's what we did tonight. We found our legs right away, and that gets you scoring easier and skating better."
Kopitar snapped a four-game scoreless skid with an assist in the second period on the goal by Doughty, the teenager who has seven goals this season after scoring six as a rookie last season. With an opening-minute goal from Philadelphia waiver-wire castoff Randy Jones, along with Brad Richardson's second of the season, the Kings are mining alternative fuel sources to get them going again.
"Obviously someone has to step up when we have key guys out, but even those who didn't score played well," said Richardson, who scored on a rebound in the second period. "Guys went to the net hard and left a wide-open goal for me. Guys are going to go through droughts without scoring, so that's why we have the third and fourth lines to pick up the slack."
Justin Williams added two insurance goals in the final 2:33. Los Angeles scored 10 goals in its first five games without Smyth before getting 10 more in its last two. Jonathan Quick helped out, making 27 saves while looking sharp in the third period.
After a swift start, Los Angeles had won two of its previous 11 games in regulation - picking up three shootout wins - before beating Anaheim 4-3 on Tuesday night. The Kings still are off to their best start in a decade, and this win put them seven games above .500 for the first time since 2005-06.
Scoring wasn't a problem against goalie Brian Elliott, who stopped 18 shots in his sixth straight start. Ottawa needs more from its former backup, who hasn't rested since Pascal Leclaire's cheekbone was broken last month by an errant puck while he sat on the bench.
"I thought we sustained the momentum after we tied it, but Brian needs to be better," Senators coach Cory Clouston said. "We needed a couple of saves, and to me, that was the difference. Brian's fighting the puck right now. He's having some adversity, or whatever you want to call it, but he's got to find a way to battle through it."
Mike Fisher scored two goals for the Senators, who have lost the first three games on a five-game West Coast trip. Jonathan Cheechoo also scored for Ottawa, giving the longtime San Jose forward 20 goals in 36 games against Los Angeles - but just three in his first 26 games with the Senators, who have lost four of five overall.
After Fisher's first of the night, Simmonds put the Kings back ahead with a precise penalty shot between Elliott's pads after he was taken down on a breakaway by diving defenseman Filip Kuba.
"When I dove for the puck, I missed it, and that was probably the key for the referee to call it," Kuba said. "I don't want to say they always call it in favor of the forwards more than the defensemen, but I guess you could call it either way."
Fisher tied it on a clever pass from Alex Kovalev, but Doughty put the Kings back ahead on a slap shot early in a power play moments later.
"It was a frustrating game," Fisher said. "I thought we did a lot of good things offensively and got some pucks to the net, but there were some breakdowns. It seemed like every chance they got, they made the best of it. We just couldn't find enough to score late. ... We got back in it after being down a couple, and we were feeling pretty good, but they stayed on the gas pedal."
Quick kept Ottawa off the board in the third, and Williams iced it when Senators defenseman Matt Carkner coughed up the puck in the corner, setting up Williams for an easy score. Williams scored again with 10 seconds left.
NOTES: Kings coach Terry Murray and his brother, Senators general manager Bryan Murray, spent Wednesday together. ... Alexandre Picard, Ottawa's top-scoring defenseman, left in the first period due to an upper body injury. ... Ottawa took three penalties in 51 seconds late in the period, but the Kings couldn't capitalize on their lengthy advantage. ... Simmonds has a five-game scoring streak, the longest of his career.