Ullmark (lower body) will not be available for Monday's tilt with the Islanders, Lance Lysowski of The Buffalo News reports.

EDGE Analysis

The Sabres are dealing with four injured goaltenders, including Ullmark, so Michael Houser will make his NHL debut Monday while Stefanos Lekkas was signed to a professional tryout agreement in order to dress as the backup. Ullmark was listed with a week-to-week injury in mid-April and there hasn't been much additional information on his status. He'll be doubtful for Tuesday's rematch with the Islanders.