Without calling the injury season-ending, coach Lindy Ruff said Ellis will miss an extended period as Buffalo prepared to host Montreal on Monday night. Ellis was hurt in a 4-3 shootout win at Ottawa on Saturday.
The Sabres will also be minus defenseman Andrej Sekera for an uncertain stretch after Ruff said the player has now been diagnosed with pneumonia. Sekera had missed the previous three games with what the team called flu-like symptoms.
On the bright side, second-leading scorer Thomas Vanek returned Monday after missing one game with an upper-body injury.