Crosby, the leading All-Star vote-getter, injured his right ankle Friday during the Penguins' 3-0 loss to Tampa Bay.
Team doctors confirmed the injury was a high-ankle sprain. The ligament injury normally requires a long recovery -- usually at least a month, and often longer.
The Penguins placed their captain on the injured list Monday, a procedural move that allowed them to add an extra forward for their two games before the break. The move was retroactive to Friday.
Tuesday's prognosis suggests Crosby, last season's scoring champion and MVP, will be sidelined until sometime in March. The Penguins have overcome a poor start to become a prime Eastern Conference playoff contender.
Other athletes who have had a high ankle sprain -- it is common in the NFL -- say it is frustrating because rehabilitation alone can't cure it and considerable rest is needed.
Penguins goalie Marc-Andre Fleury, for example, has been out since Dec. 6 with a high ankle sprain and is not yet ready to return. When Fleury was hurt, it was estimated he would return in six to eight weeks.