You knew it was bad when it happened ... Running back Thomas Clayton, who wowed 49ers fans last year at this time with a strong preseason, suffered a torn ACL when he was hit awkwardly in Friday's preseason opener against Denver. The 49ers waived him injured on Sunday. That means that once he clears waivers the 49ers will place him on injured reserve, ending his season. Because the team has depth at running back -- Frank Gore, Glen Coffee, Michael Robinson and rookie Kory Sheets -- the 49ers don't necessarily have to add another runner. Mike Singletary today said he would monitor the situation in camp.
The 49ers did, however, have to add another fullback. With Zak Keasey out eight to 10 weeks with a broken forearm, the team signed Bill Rentmeester, an undrafted rookie who spent some time this offseason with San Diego. Rentmeester was wearning No. 43 in today's walk-through.
There was some good news ... Linebacker Patrick Willis, who has missed all but one training-camp practice with a sprained ankle, will rejoin the team tomorrow, Singletary said. He stressed that he would continue to keep on eye on his defensive star. Also, Delanie Walker is set to return from the concussion he suffered when he butted heads with Justin Smith in practice. Cornerback Tarell Brown will commence running, but he will not practice. David Baas (foot) and Robinson (groin) continue to be day to day.
-- Matt Barrows