SANTA CLARA -- The Miami Dolphins are not expected to have their two starting offensive tackles available for their matchup Sunday against the 49ers.
And, suddenly, the availability of the 49ers' best offensive lineman is in question, too.
All-Pro left tackle Trent Williams left the field Friday at the beginning of practice with what the team described as a back condition. His availability for the 49ers' Week 13 matchup against the Dolphins is questionable, 49ers coach Kyle Shanahan announced Friday, and will be determined with how his back responds over the next two days.
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SIGN UP HERE If Williams is unable to play, backup Colton McKivitz is likely to get the starting assignment.
Wide receiver Deebo Samuel (quadriceps) is also listed as questionable for Sunday's game. He was not on the practice field Friday as his teammates began warmups.
Samuel was later seen on the field and in uniform, but it was unclear whether he would take part in limited practice.
Running back Christian McCaffrey, who experienced knee irritation in the 49ers' 13-0 victory over the New Orleans Saints on Sunday, was seen running at full speed and catching passes at the beginning of the 49ers' on-field work Friday and has been cleared to play against the Dolphins.
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Defensive tackle Arik Armstead said on Thursday that he will return to action Sunday and Friday's injury report confirmed he has been cleared. He has not played since Oct. 3 due to plantar fasciitis in one foot and a hairline ankle fracture in his other.
Defensive end Charles Omenihu and guard Spencer Burford also are questionable for Sunday's game, while quarterback Jimmy Garoppolo (knee) was cleared to play. Running back Elijah Mitchell (knee) is listed as out.
The Dolphins announced their injury report for Sunday's game. Starting right tackle Austin Jackson (ankle) is out, while starting left tackle Terron Armstead (toe/pec) is listed as doubtful.
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