One of the 49ers' undrafted rookie running backs exited San Francisco's preseason tilt vs. the Raiders via the cart.

Some of the team’s injuries in the preseason are just bad luck. Knee injuries to Leonard Floyd and Yetur Gross-Matos last year and injuries to Corey Kiner (high ankle) and Dominick Puni (knee) this month aren’t part of any systemic issue. They’re just misfortune.

RG Dominick Puni suffered a PCL injury and is uncertain to be ready for Week 1. RBs Patrick Taylor, Corey Kiner also hurt.

Dominick Puni is believed to have injured his posterior cruciate ligament and could miss a few weeks, coach Kyle Shanahan said after Saturday's preseason game.

The injury-riddled 49ers do have some players worth watching in Saturday’s preseason visit to the Raiders after possible cameos by select starters.

An undrafted rookie running back caught Kyle Shanahan's eye, and Marques Sigle's ascent at safety is putting pressure on two veterans.

The 49ers are banged up everywhere, but the situation at running back opens a door for undrafted rookie Corey Kiner.