San Francisco 49ers center Daniel Kilgore is scheduled to undergo season-ending surgery Tuesday for a fractured left ankle sustained in the third quarter of Sunday night's loss at Denver.

Coach Jim Harbaugh says the injury is similar to what nose tackle Ian Williams suffered in Week 2 of the 2013 season at Seattle that required four operations and kept him sidelined until training camp. Kilgore was hurt when linebacker Brandon Marshall inadvertently ran into his lower leg at the end of a run by Frank Gore during a 42-17 loss to the Broncos.

Marcus Martin, a 20-year-old rookie third-round draft pick, is the favorite to fill in for Kilgore on the starting offensive line. Martin recently returned to practice following a training camp knee injury.

Martin's NFL debut would likely be Nov. 2 at home against the Rams after the bye.

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