SAN DIEGO - The Chargers escaped a potentially devastating loss on Monday when a foot injury suffered by Pro Bowl defensive tackle Jamal Williams was discovered to be only a sprain.

Williams injured the foot during Sunday's exhibition loss to Seattle. He underwent an MRI on Monday, and the exam ruled out a more serious injury. Williams is considered day to day.

His availability for Saturday's exhibition game at St. Louis has not yet been determined.

Williams, 31, has played in the past two Pro Bowls and is considered one of the top defensive tackles in the NFL. He had 84 tackles last season, third most on the Chargers.

Before receiving the MRI results, coach Norv Turner professed to being worried about Williams' injury.

"I have a concern any time someone says it's a foot injury," Turner said.

Also disclosed Monday was that linebacker Anthony Waters strained a knee during Sunday's game. The good news for Waters is that the injury was to his right knee and not his left.

Waters, a third-round draft pick from Clemson, tore the anterior cruicate ligament in his left knee last September.

Safety Eric Weddle, who suffered a slight ankle sprain, is expected to play against the Rams. The other players hurt in Sunday's game were cornerback Steve Gregory (quadriceps contusion) and linebackers Marques Harris (shoulder) and Jyles Tucker (concussion).