Niners lose NT Williams for the season

San Francisco 49ers defensive tackle Ian Williams is undergoing surgery on his broken left ankle on Monday and will miss the rest of the season.

The first-year starter had the ankle rolled over in the first half of the Niners' 29-3 loss to Seattle on Sunday. He did not return to the contest after exiting and will eventually land on season-ending injured reserve.

The loss of Williams leaves San Francisco with just five healthy defensive lineman. Glenn Dorsey, who stepped in for Williams to record five tackles and a sack, is expected to start at nose tackle this week.

In other injury related news, Niners coach Jim Harbaugh said rookie safety Eric Reed is showing no concussion symptoms a day after taking a blow to the head while making a tackle on Seattle wide receiver Sidney Rice.

Reid will still have to pass the NFL's concussion protocol in order to suit up for the Niners' upcoming contest with the Indianapolis Colts this Sunday.