The 49ers fear that star quarterback Jimmy Garoppolo suffered a major ACL injury in the team’s 38-27 loss to the Chiefs on Sunday afternoon. Garoppolo left the game early after taking a hit near the sideline on which he appeared to suffer a leg injury. He was carted off the field and briefly replaced by C.J. Beathard, who may be taking over full-time duties going forward.

Following the game, 49ers coach Kyle Shanahan told reporters that the team fears it’s a significant injury.

Beathard also made comments suggesting it’s not good for Garoppolo.

As the NFL Network reports, Garoppolo will undergo an MRI on Monday to determine the damage. If the quarterback suffered an ACL tear, he’ll miss the remainder of the season. Other quarterbacks who recently suffered ACL tears include Philadelphia’s Carson Wentz and Houston’s Deshaun Watson. Both of those players have recovered in time to return to their teams this season, but it’s a long road back.

Here’s the play on which Garoppolo suffered the injury:

Garoppolo, 27, became the 49ers’ starting quarterback after a midseason trade from the Patriots last year. The team posted a 6-1 record in his starts entering Sunday. He had completed 20 of 30 passes for 251 yards and two touchdowns against the Chiefs prior to leaving the game. Through two-plus games this season, he had thrown for 718 yards with five touchdowns and three interceptions.