San Francisco 49ers outside linebacker Ahmad Brooks will be out at least two weeks because of a lacerated kidney.
Brooks was hurt during Friday's morning practice. The injury originally was diagnosed as a bruised rib before tests revealed more extensive damage Saturday.
Brooks, who signed a two-year, $4.225 million contract extension in March, had a breakout season in 2009, when he recorded a career-high six sacks and tied a franchise record for a linebacker with four forced fumbles.
Brooks became a regular during third-down pass-rushing situations over San Francisco's final six games, recording five sacks in the last five games. The 49ers were grooming Brooks for a more extensive role this season, but his injury already is testing the team's depth at linebacker, two days after it likely lost Scott McKillop for the season.
The 49ers have Patrick Willis, Takeo Spikes, Manny Lawson and Parys Haralson leading a group of 13 linebackers at training camp. The team also has veterans Travis LaBoy and Matt Wilhelm in the mix.
The Associated Press contributed to this report.