Ruff sustained three broken ribs following the run-in with Leopold at First Niagara Center in Buffalo where the Sabres were preparing for Wednesday's contest with the Boston Bruins, a statement indicated.
The coach had to be helped off the ice but "is expected to be back tomorrow to resume his coaching responsibilities," the team said.
Leopold lost his balance while working on a 1-on-1 drill with teammate Ville Leino, sliding into Ruff from behind, The Buffalo News reported.
The Sabres coach flew into the air and landed hard on the ice, yelling out in pain, the newspaper said.
Scarlett Johansson steps out with fiance after pregnancy reveal
Dennis Rodman pledges to end trips to North Korea