Broncos cornerback K’Waun Williams will undergo another surgery Monday on his troublesome left ankle and has been ruled out for the season.

Williams had surgery performed by Dr. Robert Anderson at the OrthoCarolina Foot & Ankle Institute in Charlotte, N.C., on Aug. 28 and it was thought then that he could return midway through the NFL season. However, sources said Friday it was determined that the surgery performed then did not result in the ankle being strong enough for Williams to return this season. So Anderson will perform another surgery at his clinic, and it is expected Williams will need 12 weeks to recover.

Williams had been working out on a side field in recent weeks during Denver practices. However, he was not out on the field this week after it was determined he did not regain enough strength in his left leg. It was then diagnosed by Anderson that it was a structural issue, requiring another surgery.

Williams, who has played eight NFL seasons, was Denver’s primary nickel back last season. That role went this season to Essang Bassey for the first three games and then to Ja’Quan McMillian for the past three games. Bassey since has been waived and claimed by the Los Angeles Chargers.

Williams had issues prior to this season with his left ankle. He hurt it again early in training camp and missed the entire preseason, setting the stage for the Aug. 28 surgery. He was placed on injured reserve after the initial 53-man roster was set, meaning he would have been eligible to return this season after missing at least four games.