Jonathan Williams injured his foot in Arkansas' scrimmage on Saturday. He took a big hit late in the practice and walked off the field. It didn't seem significant at the time although he didn't return. Bielema said afterward he wasn't sure what happened but it looked like he had a "tender ankle".
Apparently it's a much bigger deal than initially thought because Williams' injury requires surgery and he'll be out for "an extended period of time during the 2015 season."
The press release from Arkansas does not state what exactly the injury is nor give any indication as to what an "extended period of time" means.