Coach Phil Housley didn't go into much detail Tuesday, saying Sheary was injured while being checked during the first day of training camp on Friday. Sheary is listed week-to-week.
The injury is a setback for the Sabres, who were counting on Sheary playing on one of the top two lines after acquiring the forward in a trade with Pittsburgh in June. Sheary is a two-time Stanley Cup winner and has 48 goals and 93 points in 184 games.
Forward Sean Malone will miss up to six weeks after hurting his knee in the second period of Buffalo's 4-1 preseason win at Columbus on Monday.
The Sabres also announced defenseman Matt Hunwick will be out indefinitely with a neck injury. He has been out since the start of camp. Housley didn't reveal how or when Hunwick was hurt.
Hunwick was acquired in the trade with Sheary from Pittsburgh.