Craig Anderson signed a one-year, $700,000 contract with the Capitals on Wednesday.
The 39-year-old goalie was placed on waivers and will join goalies Pheonix Copley and Zach Fucale on the taxi squad if he clears at noon ET on Thursday.
Goalie Ilya Samsonov is expected to start for Washington in its season-opener at the Buffalo Sabres on Thursday (7 p.m. ET; ESPN+, SN360, SNE, SNO, MSG-B, NBCSWA, NHL.TV).
Vitek Vanecek, a 25-year-old rookie, made the roster as Samsonov's backup.
Anderson signed a professional tryout contract with the Capitals on Dec. 27 after Henrik Lundqvist announced Dec. 17 he would be unable to play this season because of a heart condition that later required open-heart surgery. Anderson was 11-17-2 with a 3.25 goals-against average and .902 save percentage for the Ottawa Senators last season.
"Anderson, I thought, played really well in the scrimmage and Copley, I thought, was real strong throughout the camp," Capitals coach Peter Laviolette said. "So these guys are available to us, but right now this is the decision we made with these two kids. They've worked hard to get to this position to gain an opportunity and now they'll get a chance to show what they can do."