49ers leave 53-man roster spot open after placing CMC on IR

MINNEAPOLIS — The 49ers did not make a roster move Saturday to fill Christian McCaffrey's 53-man roster spot. San Francisco will go with three active running backs against the Minnesota Vikings on Sunday, led by starter Jordan Mason. The 49ers placed McCaffrey on injured reserve with calf tightness and Achilles tendinitis, which makes him ineligible for the next four games. San Francisco now has one open 53-man roster spot. The 49ers again elevated veteran safety Tracy Walker III from the practice squad to provide depth with Talanoa Hufanga not expected to play. Hufanga is listed as doubtful for the game as he continues to round into condition after undergoing season-ending surgery in his torn right ACL in November. George Odum is expected to remain as the starting safety alongside Ji'Ayir Brown until Hufanga is cleared to return to action. The 49ers will again lean heavily on Mason as the lead back. He gained a career-high 147 yards and scored a touchdown on 28 rushing attempts in the 49ers' 32-19 Week 1 victory over the New York Jets. Wide receiver Deebo Samuel also could get some carries from the backfield or on jet sweeps. He had 23 yards and a touchdown on eight rushes...