"He ended up breaking something in his hand," Shanahan said. "Part of his thumb. He's going to have to get a procedure here so he'll be questionable for Seattle."
Shanahan was asked if Colbert could play with a cast.
"I believe there's a chance," Shanahan answered. "We don't think he'll be out too long. He did it early in the first quarter. He played through the whole game with it. It was extremely tough of him but it's something that you have to get fixed right away. You don't want to play with it or it could heal wrong so we've got to get that fixed right away. He possibly could miss the Seattle game but I feel pretty good about him after that."
Colbert has 17 combined tackles and three passes defensed through nine games this season. He owns Pro Football Focus' highest run defense grade among 49ers safeties and the second-highest among the team's defensive backs this season.
The 49ers originally intended to use Colbert as a cornerback because of need and perceived fit. Once he moved to safety, the rookie began to shine, and the coaching staff quickly took notice.
Last week, 49ers defensive coordinator Robert Saleh spoke to reporters about his young safety and shared what makes him so special.
"He's relentless in his work ethic and his preparation," Saleh said. "I love the way he hits. He's a very physical football player, and it's very important to him. I don't know if it's a chip (on his shoulder) as much as it is important where every rep, every play, every meeting, is very, very important. He's very into it, and he has something to prove, for sure."
The team is already down two other safeties. Both Jimmie Ward and Jaquiski Tartt are on injured reserve with broken arms.
Shanahan also provided an update on C.J. Beatahrd's thumb, saying the rookie quarterback didn't suffer any fractures.
"Pretty banged up," Shanahan said of Beathard. "He'll be sore throughout this week. It will definitely help to let him get some rest because nothing's broken or anything. Make sure no one runs into it over the next week will help and it should be better next week Monday."
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