Rams guard Jamon Brown (right) fractured his lower leg while offensive tackle Rob Havenstein suffered a calf injury. Jeff Roberson AP Photo

St. Louis Rams rookie offensive guard Jamon Brown suffered a fractured lower leg late in the second half of Sunday's 37-13 loss to the Chicago Bears.

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Brown was carted off the field with four minutes remaining in the contest following an attempted tackle on an interception return by Chicago linebacker Willie Young. Rams coach Jeff Fisher said Brown is likely done for the season.

The 6-foot-4, 323-pound Brown, who has started all nine games for St. Louis, grabbed at his leg after it was twisted underneath him. Trainers placed an air cast on the leg when Brown was taken off the field.

St. Louis also saw right tackle Rob Havenstein exit the game with a calf injury. Havenstein was back in the lineup Sunday after sitting out Week 8 due to an ankle injury. The Rams have already lost starting guard Rodger Saffold to a season-ending shoulder injury.