Hall is averaging 25.2 yards on kick returns, including an 84-yarder, and is third in the NFL with a 15.1-yard average on punt returns, with an 85-yard touchdown. He also has four receptions for 27 yards.

"He'll be week to week," coach Scott Linehan said. "Certainly it does not look like he'll be available for this game, but we'll see how he responds to treatment."

The injury is significant enough that the Rams signed a new return man, Brandon Williams, cut late last month by the 49ers. Linehan said Williams, who is from St. Louis and was a third-round pick in 2006, could be ready as soon as this week and also could help at wide receiver.

"I think people around here are familiar with Brandon, know what kind of career he's had," Linehan said. "With the likelihood that Dante is going to be missing some time for us, we wanted to back ourselves up with another returner."

The injury, sustained when an opposing player fell on Hall during a return, thrusts second-year player Marques Hagans into triple duty. Hagans will replace Hall on kick and punt returns, and at wide receiver, if needed. Plus, he's also been pressed into service as the third quarterback since Marc Bulger was sidelined with two broken ribs last week.

Wide receiver Dane Looker, also the holder on kicks, was ruled out for the second straight week with a deep thigh bruise that has required blood transfusions. Looker was injured when he slid across artificial turf two weeks ago at Dallas.