SANTA CLARA, Calif. - The 49ers lost one nose tackle for the year and activated another.
Ian Williams, who fractured his left fibula in Nov. 9's win over the New Orleans Saints, was placed on injured reserve Monday. Williams is being shelved with a fracture to his left leg for the second straight season after breaking his ankle in the team's second game of 2013. His recovery required four surgeries before returning in training camp last summer after missing the offseason program.
Fellow nose tackle Glenn Dorsey was elevated to the active roster Monday, which was likely to happen regardless of Williams' injury. Dorsey was placed on IR with the return designation after suffering a biceps tear in the first weekend of training camp. The deadline to activate Dorsey or shut him down for the season was coming Tuesday.
At the start of 2013, Williams broke camp as the starter over Dorsey despite the former Chief's first-round pedigree. Dorsey was the fifth-overall pick of the 2008 draft, but never lived up to that billing after undergoing position changes while Kansas City went through turnover at defensive coordinator.
Williams joined the 49ers as an undrafted free agent in 2011 and spent time over his first two seasons developing on the practice squad.
After adapting to nose tackle under San Francisco's defensive line coach Jim Tomsula, Dorsey blended into the defense well in his first season after signing a free-agent deal. In August, the 49ers inked Dorsey to a two-year extension through 2016 worth a reported $6.075 million after his strong showing in Williams' place last year.
Dorsey played 42 percent of the 49ers' plays last season and graded out as the team's top run defender by Pro Football Focus. San Francisco has been the NFL's sixth-ranked run defense in 2014.