Jimmy Garoppolo took the league by storm late last season when he won his first five starts as the 49ers' quarterback. His rough start through the first two games of the 2018 season was made immeasurably worse during the fourth quarter of the 49ers' Week 3 matchup against the Chiefs.

Garappolo scrambled near the sideline and instead of going out of bounds, he planted his left foot to stay in bounds and his left knee appeared to buckle in the process.

Not helping: Garoppolo took a head shot for good measure. He remained on the turf for several minutes before making his way to the locker room on a cart.

After the game (the 49ers lost, 38-27) coach Kyle Shanahan told reporters, "With Jimmy we're fearing [an] ACL [injury]. We'll find out tomorrow [after he undergoes an MRI]."

It would be a devastating development for a team many expected to be much-improved over last year's six-win team, and perhaps even good enough to make a playoff push for the first time since 2013, when Colin Kaepernick took San Francisco to the NFC Championship Game. That was also the last time the 49ers had a winning record. 

Instead, the 49ers have fallen to 1-2 on the season and their franchise quarterback could be facing a nine-month recovery if he has, in fact, suffered an ACL injury. This development comes three weeks after Jerick McKinnon, signed in the offseason to four-year, $30 million deal, tore his ACL.

If Garoppolo is sidelined, backup quarterback C.J. Beathard would replace him in the lineup. 

Beathard, a 2017 third-round pick out of Iowa, appeared in seven games last season (five starts), and completed 54.9 percent of his throws for 1,430 yards, with four touchdowns, six interceptions and a passer rating of 69.2.