Kyle Williams has confirmed that he tore his anterior cruciate ligament in the San Francisco 49ers' game against the New Orleans Saints on Sunday.
The wide receiver missed the end of the game after picking up the injury in the third quarter.
The 24-year-old said on Twitter: "Regret to inform [you all] I will be out for the season with a torn acl.
"Not how I saw things playing out but in the end I will be fine and [this] is just another obstacle I will have to climb to get back."
Williams has mainly featured on the 49ers' special teams this season as a punt returner.