Williams was selected with the seventh overall pick in the 2017 NFL Draft.
It was reported by NFL.com that Williams will likely begin training camp on the physically unable to perform (PUP) list.
The 22-year-old underwent a second epidural in hopes of expediting his recovery, but the Chargers are preparing for his absence at training camp, Schefter reports.
The Chargers are unsure when Williams suffered the back injury but diagnosed him with a herniated disk after the first rookie minicamp session.
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