McCollum suffered the injury in the first half of Lehigh's loss to VCU on Saturday. An X-ray revealed that the senior has a fractured fifth metatarsal in his left foot.
"Recovery time is estimated at eight to 10 weeks," Lehigh coach Brett Reed told ESPN. "We are going to make sure C.J. is fully recovered and will place the highest priority on quality of care and be certain the injury has healed properly before full activity is resumed."
Reed said Saturday that McCollum has had problems with ankle sprains in the past but acknowledged that the injury probably was a broken foot.
Reed's suspicions were confirmed Sunday, as Lehigh (9-4) may have to play the remainder of the regular season without its best player.
A preseason All-American, the 6-foot-3 McCollum is averaging 23.9 points per game, the second-best mark in Division I, and is a two-time Patriot League Player of the Year. He scored 30 points last March to lead Lehigh to a stunning first-round upset of second-seeded Duke in the NCAA tournament.
ESPN.com's Andy Katz and The Associated Press contributed to this report.