Coach Kyle Shanahan said Saturday that Mason has a sprained foot but is considered day-to-day, Josh Dubow of The Associated Press reports.

EDGE Analysis

The 49ers backfield has had its share of injuries during training camp and the preseason, with Elijah Mitchell missing significant time with an adductor strain and Jeremy McNichols dealing with a hamstring issue. Now, one of the competitors for the No. 3 spot behind Christian McCaffrey and Mitchell is tending to a health concern. San Francisco likely will keep four running backs on its final 53-man roster following cut-down day Tuesday, while Mason could be sidelined in the short term with the aim to be healthy by Week 1.