Luukkonen left Saturday's 3-1 preseason loss against Pittsburgh because of an undisclosed injury, per Mike Harrington of The Buffalo News.
Luukkonen's issue was described as a "tweak" and the decision to pull him precautionary, so it's still possible that he'll be available for Buffalo's season opener in Columbus on Thursday. However, the timing is especially bad for the Sabres, who were already missing Alex Lyon (upper body). If Lyon and Luukkonen are both unavailable for the start of 2026-27, then Colten Ellis would likely be leaned on heavily at the beginning of the campaign.