Samkon Gado

Samkon Gado, who had clearly distanced himself from Kenneth Darby and Antonio Pittman, the other primary contenders for the backup job behind Steven Jackson, suffered cartilage damage to his ribs in the 17-9 preseason win over KC. Although X-rays showed no fracture, that’s still a significant injury for a running back.

Spagnuolo said Monday that Gado probably was questionable for the regular-season opener Sept. 13 in Seattle. Beyond that, no one knows yet. Gado’s a tough cookie, and he might bounce back quickly. But this is also the kind of injury that could lay him up for a while.