Karlsson, who hasn't played since Jan. 16 because of a groin injury, practiced Wednesday and is getting close to returning to the lineup.
The Sharks, who are going for their second seven-game winning streak this season (Jan. 2-15), are tied with the Calgary Flames for first in the Pacific Division and with the Winnipeg Jets for first in the Western Conference. Their six-game winning streak began with a 7-6 overtime win in Washington on Jan. 22.
The Capitals began a five-game road trip with a 3-0 loss to the Columbus Blue Jackets on Tuesday after going 4-1-1 on a six-game homestand. They are in second place in the Metropolitan Division with 69 points, three behind the New York Islanders and two ahead of the Blue Jackets and Pittsburgh Penguins.