Joe Thornton scored for the Sharks, who lost in regulation at home for the first time in five preseason games.
Los Angeles' Jonathan Quick stopped 16 of 17 shots in two periods in his first preseason game appearance. Martin Jones saved all seven shots he faced in the third period.
Antti Niemi went the distance and made 26 saves, but took the loss.
The teams will open the regular season against each other on Oct. 8 in Los Angeles.