Head coach Lindy Ruff said Wednesday that Zellweger has entered the concussion protocol, Paul Hamilton of WGR Sports Radio 550 reports.
Zellweger suffered a concussion during Tuesday's preseason game against the Blue Jackets and will now be sidelined while he works to clear the league's protocol. It's not yet clear whether Zellweger will be available for the Sabres' Opening Night matchup against Columbus on Oct. 1, but it seems likely that he'll at least be sidelined for the team's final two preseason games.