49ers DT Ian Williams out for season with broken left ankle

49ers defensive tackle Ian Williams broke his ankle in his first career start and is out for the season. (Michael Zagaris/Getty Images)

San Francisco 49ers defensive tackle Ian Williams is out for the season with a broken left ankle, the team announced Monday. The team confirmed initial reports Sunday night, which said Williams had suffered a broken ankle on a low block during the 49ers' 29-3 loss to the Seattle Seahawks.

“It was an unfortunate play,” 49ers head coach Jim Harbaugh said of the block that ended up finishing Williams' season.

Williams was injured on the play in the first quarter in which he was blocked low by Seattle right guard J.R. Sweezy.

The 24-year-old Williams has played in five games during his three-year career with the 49ers. Sunday was his first career start.

Williams was replaced by Glenn Dorsey, a former top-five pick by the Kansas City Chiefs who signed with the 49ers as a free agent in the offseason. His absence leaves the 49ers with only five healthy defensive linemen.