San Francisco 49ers running back Matt Breida is a game-time decision for Sunday’s game against the Los Angeles Chargers because of a knee injury.Breida, who is tied for the NFL rushing lead with 274 yards, was listed as questionable on Friday’s injury report. But coach Kyle Shanahan said the decision on whether Breida plays will be made on Sunday.”Just to see how he feels on game day,” Shanahan told reporters. “He’s been up and down a little bit this week. He got a little bit more (work Thursday). We kept him limited (Friday) just trying to manage the wear and tear. But questionable is better than doubtful, so hoping it works out.”Breida is fine with letting the situation play itself out.”I’ve got to feel comfortable,” Breida told reporters. “It’s a long season.”The possibility of not having the league’s top rusher — Breida is tied with Ezekiel Elliott of the Dallas Cowboys — comes as quarterback C.J. Beathard makes his sixth career start in place of Jimmy Garoppolo (season-ending knee injury).Next in line at running back behind Breida is Albert Morris, who also is listed as questionable with a knee injury.Cornerback Richard Sherman (calf) and guard Joshua Garnett (toe) were ruled out of the contest. Safety Jaquiski Tartt (shoulder) is doubtful and safety Adrian Colbert (hip) is questionable.