KANSAS CITY, Mo. _ Jimmy Garoppolo sustained a left-knee injury just before a sideline hit Sunday during the 49ers' fourth-quarter comeback attempt, and the 49ers are proceeding as though it's a season-ending tear of his anterior cruciate ligament.
"It's a knee. We fear an ACL," coach Kyle Shanahan said. "We'll find out for sure (Monday)."
Garoppolo's left leg twisted awkwardly as he planted his foot just before a helmet-to-helmet collision with cornerback Steven Nelson at the Chiefs 7-yard line. It was a fateful scramble for 13 yards on third-and-goal with 5:27 remaining.
Garoppolo will have an MRI on Monday. He did not speak with the media afterward, and although Reuben Foster and a few players offered best wishes to him in the training room, many players didn't know where he was before he eventually got carted up toward the team bus.
C.J. Beathard, who replaced Garoppolo for the 49ers' remaining snap, said he talked to him in the training room and told him he'd be "praying for him."
"Anytime you lose your starting quarterback _ I mean it's, everyone _ it is a big deal," Shanahan said. "It was when we lost our starting running back, too."
The 49ers saw an ACL tear also rob them of running back Jerick McKinnon, the 49ers' high-priced addition and dual-threat asset who got hurt a week before their season opener. McKinnon responded on Twitter to Garoppolo's injury with a simple emoji, one of a sad face.
"I feel for him personally. I know how disappointed he is," Shanahan added.
Shanahan and several players initially thought Garoppolo sustained a concussion as he was tended to by trainers on the field for several minutes. He walked slowly to the 49ers sideline and into the medical evaluation tent. His left leg was fully extended as he got carted off the field.
Garoppolo got sacked on the previous two plays, and he escaped the pocket to try running for the goal line on third-and-goal. He made it 13 yards. No penalty was called on the play.
"Jimmy was just trying to make a play," left tackle Joe Staley said. "We're trying to make a comeback. We felt we had the momentum, we felt we were going to get a touchdown on that drive and make it a seven-point game.
"Jimmy's just trying to be a ballplayer and trying to make a play. He wasn't running out of bounds. He was trying to get some extra yards for his team. It's just one of those things."
