The perennial Pro Bowl pick and No. 1 overall choice in the 2008 draft was hurt in Sunday's loss to New England. Long might have played his final game for Miami because he can become an unrestricted free agent this winter.
Rookie right tackle Jonathan Martin will make his first start on the left side Sunday at San Francisco. He played left tackle at Stanford.
Nate Garner, who has nine career starts, takes over at right tackle.
Long would receive $15.4 million next year if the Dolphins give him a franchise tag, and that's likely more than Miami will be willing to spend. He has battled injuries for much of his career and had a disappointing season.