Which players on the San Francisco 49ers roster are firmly on the bubble with one week to go until roster cutdowns start?

For the 49ers their health has become a greater concern than their preseason performance. They just need to make sure they have enough healthy bodies to keep their key starters out of harm's way. More than 20 players missed their preseason opener vs. the Denver Broncos with injuries, and that number could rise Saturday when they face the Raiders.