Fields, the Associated Press' reigning Big 12 defensive player of the year, will seek a medical redshirt. If he gets one, Fields would still have three years of eligibility remaining.
This has been a nightmare season for Fields, who led the Big 12 as a freshman last season with 18.5 tackles for a loss. He didn't play in TCU's opener against LSU and played just one quarter the following week against Southeastern Louisiana while serving out a suspension after breaking unspecified team rules in the spring.
In TCU's third game, Fields suffered the foot injury at Texas Tech. He tried to return last weekend at Oklahoma, but was ineffective.
TCU, which received preseason votes to win the Big 12, is 2-3. The Horned Frogs also lost quarterback Casey Pachall to a broken arm in their second game.