The St. Louis Rams will be without No. 1 wide receiver Donnie Avery for four to six weeks after the second-year player injured his foot during a scrimmage last week.
Avery was hurt Friday and has a stress fracture in his left foot, the team said. The injury could mean he'll miss the first two regular-season games.
"We'll take it day by day, but it's going to be a lot of time," Rams Coach Steve Spagnuolo said.
Former Kentucky standout and second-year player Keenan Burton, veterans Tim Carter, Laurent Robinson and Ronald Curry, and rookie Brooks Foster are among the nine wide receivers in camp fighting for roster spots.
Burton and Robinson worked with the starting unit in Sunday's workouts.
"Any time anybody goes down, you have to step your level of play up," Burton told the St. Louis Post-Dispatch. "That's from top to bottom. From the rookies, all the way up to Carter and Curry having seven years (experience). So you've got to go out and play."
Burton added: "I don't necessarily know how (Avery's injury) affects me at all. I'm going to play my position. I know all the receivers are going to play their positions. And we're going to go out here and compete."
After Torry Holt left as a free agent after last season, Avery became the Rams' top receiver. He had 53 catches for 674 yards as a rookie. He was chosen in the second round of the 2008 draft.
Burton had 13 catches for 172 yards and a touchdown as a rookie last season.
Carter did not play last year, but has 80 career catches over six seasons. Curry was signed by the Lions in April as a free agent after being released by Oakland, where he spent seven years. Robinson played the last two seasons in Atlanta.