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

Right guard Dominick Puni and running back Corey Kiner sustained significant injuries in the first half of the 49ers’ preseason visit to the Raiders on Saturday.

Multiple preseason injuries created serious questions about San Francisco’s offensive line stability and backfield depth heading into Week 1.

The Raiders have a battle raging at right guard between Jackson Powers-Johnson and Alex Cappa. But Sunday that battle was put on hold due to injury.

Also, rookie tackle Connor Colby impressed while QB Brock Purdy was sharper than he was in last week’s joint practice against the Broncos.

Unfortunately, he went down on a worrisome hit in his first preseason game against the Chicago Bears. He was later diagnosed with a neck injury. After undergoing surgery, he's been ruled out for the rest of the year but is expected to make a full recovery.