Kolosov made 19 saves in Saturday's 5-1 preseason loss to the Capitals.
After a scoreless first period, Jamie Drysdale gave the Flyers a brief lead just 31 seconds into the second, but Kolosov couldn't make it hold up. The 24-year-old netminder has a shaky 3.64 GAA and .863 save percentage over 21 career NHL appearances, but he could open the season as the No. 2 netminder behind Joseph Woll if Dan Vladar (upper body) misses any time.