San Francisco (AFP) - San Francisco 49ers quarterback Jimmy Garoppolo will miss the rest of the season after suffering torn knee ligaments in his team's defeat to the Kansas City Chiefs, the club confirmed on Monday.
Garoppolo, 26, was carted from the field after twisting his left knee awkwardly as he scrambled up the sideline on a 13-yard run towards the end of Sunday's 38-27 loss at the Arrowhead Stadium.
Head coach Kyle Shanahan confirmed a scan showed Garoppolo had suffered a torn anterior cruciate ligament.
Garoppolo's spur-of-the-moment decision to go for yardage and risk contact was criticised in some quarters but Shanahan defended his signal-caller.
"I think everyone's the same after it happens - 'Why don't you just get out of bounds?'" Shanahan said.
"I think that's a reminder to all quarterbacks and coaches. You can turn on the tape any Sunday and you're going to watch 15 plays of quarterbacks jumping over people, not getting out of bounds, doing a bit extra to move the chains."
The injury is a crushing blow for the 49ers, who was traded to the team from the New England Patriots in a shock trade last October.
Garoppolo had long been seen as the heir apparent to Tom Brady at the New England Patriots and had impressed by winning all five starts last season.
Shanahan said C.J. Beathard would take over the quarterback duties for Sunday's trip to Los Angeles to face the Chargers.
"I have a lot of confidence in C.J.," Shanahan said. "He's one of the toughest quarterbacks I've ever been around."