The Rams defense just took a big hit.

Cornerback E.J. Gaines suffered an injury that was initially thought to have been a leg injury during the first week of training camp.

However, it turned out the injury was much more serious: Gaines underwent surgery to repair a Lisfranc foot injury that will sideline him the entire year, per Jim Thomas of the St. Louis-Dispatch.

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"It's a tough break," a team source told the St. Louis-Dispatch, speaking on the condition of anonymity. "But the team will roll on. He'll be 100 percent when he comes back. We'll keep him busy and keep him occupied during his rehab."

Gaines was expected to compete with Trumaine Johnson for the starting cornerback job opposite Janoris Jenkins.

For now, though, the Rams will have to rely on Jenkins, Johnson and second-year man LaMarcus Joyner at the cornerback spots. Backing them up are Marcus Roberson and Brandon McGee, according to the depth chart.

(h/t St. Louis Post-Dispatch)