Williams tweeted about the injury Friday morning just after the team announced it signed receiver Chad Hall to the 53-man roster and placed Williams on IR. Williams played in 39 games with nine starts in more than three NFL seasons with San Francisco and Kansas City. His only appearance for the Chiefs came in last week's loss to Denver.
Williams was claimed off waivers from the San Francisco 49ers a day earlier, and didn't arrive in Kansas City until after midnight. He spent his first day in the practice facility trying to get up to speed in time for Sunday night's showdown against the Broncos. It's possible that he'll be able to play on special teams, but Chiefs offensive coordinator Doug Pederson said it would be unfair to expect Williams to contribute on that side of the ball.
Williams' agent, Wynn Silberman, says the move has been made by the reigning NFC champions, though the 49ers had yet to formally announce Williams' departure. San Francisco (6-3) is looking for more production in the passing game, and Williams had fallen on the depth chart with the return of Mario Manningham for Sunday's 10-9 loss to the Carolina Panthers.