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Kansas City Chiefs linebacker Justin Houston says Jimmy Garoppolo has no one to blame but himself if he suffered a season-ending knee injury as feared.

"That was his fault," Houston told reporters. "I pray he's not hurt, nothing serious, but as a quarterback you should step out of bounds. It was only an inch. That inch wouldn't have made a difference. You got the yardage you need, you step out of bounds. You got to be smart."

Garoppolo went down in the fourth quarter of Sunday's 38-27 loss to Kansas City when he attempted to cut back inside on a scramble to avoid Chiefs defenders. The San Francisco 49ers quarterback was carted off the field, and coach Kyle Shanahan confirmed the team fears he has a torn ACL.

"All indications are that it's torn," 49ers general manager John Lynch told NBC Sports' Peter King. "Our [medical] guys say they've been wrong before and so they need to do the MRI, obviously."

Watching the replay, Houston has a point. Garoppolo could have stepped to his left and been out of bounds untouched. Instead, he was injured trying to cut back to the middle of the field for a possible gain of one or two more yards.

The longtime backup of Tom Brady, who won all five of his starts after coming over via midseason trade in 2017, had gotten off to a rocky start this year. Garoppolo threw for 718 yards and five touchdowns against three interceptions in his three starts, and even those numbers are a bit misleading. Most of his production through the air against Kansas City came after the Chiefs built a 35-7 lead.

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The 49ers will hand the starting reins over to C.J. Beathard, a 2017 third-round pick who threw for 1,430 yards and four touchdowns against six picks last season.

"I'm not worried at all about C.J.," tight end George Kittle told reporters. "He's a hell of a quarterback. He knows how to win. So I'm not worried about that at all. He's going to step right in and he's going to do just fine.

"Coach Shanahan has the highest standards for every single person on the team, especially C.J. That's why they took him in the third round; they thought so highly of him. And he did his job last year, and he's going to step up and do it again no matter what happens."

Beathard threw for 5,562 yards and 40 touchdowns during his time at Iowa.