Leach had started three games
The 6-foot-11 senior was injured with about nine minutes left in regulation in Saturday's overtime victory over Xavier. He said he hurt his knee when he landed on a player's foot while trying to block a shot.
Indiana (2-1) did not release any other information about the injury.
"This is unfortunate for George personally, as well as for our team," coach Mike Davis said in a statement. "We need George's defensive presence in the low post. Hopefully, he can help us in the Big Ten season."
Leach led the Big Ten last year with 79 blocks and is fifth on the Hoosiers' career list (155). He started the first three games this season, posting season-highs of 11 points and five blocks at Vanderbilt. He was averaging eight points.
Copyright 2003 by The Associated Press