Eichel was reevaluated after not playing in a 5-4 shootout loss to the Philadelphia Flyers on Tuesday. The center was expected to be out at least 7-10 days.
"I would say he is out for the foreseeable future, and because of the nature of the injury we can't put a fixed date on that," Sabres coach Ralph Krueger said Saturday. "We're expecting it to go on a little longer."
Eichel previously missed two games with a lower-body injury Feb. 25 and Feb. 27. The Buffalo captain was third on the Sabres with 18 points, one behind forwards Sam Reinhart and Victor Olofsson, and scored two goals in 21 games, the fewest to start his six-season NHL career.
Asked if the injury could keep Eichel out for the rest of the season, Krueger said he wasn't sure.
"I'm being honest with you, we do not know for certain the time frame on it," he said. "We just know that it will be some time here from shorter all the way to what you've already mentioned. Nobody in the National Hockey League speaks specifically about injuries unless they're season-ending, and if it did become that we would be able to address it in a different way."
The Sabres (6-16-4) have been outscored 40-17 during a 10-game losing streak (0-8-2), including a 3-0 loss to the Pittsburgh Penguins on Saturday.
Buffalo is 2-12-2 since Feb. 15, when it returned after having six games postponed due to NHL COVID-19 protocols.
"Of course Jack Eichel is an absolute elite player in this league who drives, when he's healthy, a lot of the power that makes the Sabres a threat to other teams on a given night," Krueger said. "Now we need to work together. But my focus truly, truly, from here forward is on the group that's here, on continued growth within this group, and on us playing a really connected game."
NHL.com independent correspondent Heather Engel contributed to this report
