Photo by Phil Ellsworth / ESPN Images(SAN DIEGO) — Rookie wide receiver Mike Williams could require back surgery that could endanger his rookie season.

ESPN reports that Williams recently received a second epidural to help deal with a herniated disk.

Williams was drafted seventh overall by the San Diego Chargers. He showed up to the team’s rookie minicamp with a bad back.

After one practice, he was diagnosed with a herniated disk.

Chargers coach Anthony Lynn had publicly expressed hope that Williams could heal with rest. ESPN reports that Williams got some relief from the recent epidural, but that concerns about his back remain.

Williams suffered a fracture in his neck during his time at Clemson. He missed much of the 2015 season with that injury, but returned last year to play a major role in the team’s first NCAA Championship in more than 20 years.