The 49ers got the news they feared on Monday.

Jimmy Garoppolo did indeed tear his ACL in San Francisco’s Week 3 loss to the Chiefs. The franchise quarterback was in his first full season as a starter following three-plus seasons as Tom Brady’s understudy with the Patriots before he was traded to the 49ers almost a year ago.

Garoppolo suffered the injury while sneaking to the sidelines in the fourth quarter.

“That was his fault,” Chiefs linebacker Justin Houston said after the game. “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 won all five of his starts last season, leading to a $137.5 million contract this past offseason. The 49ers are 1-2 this year.