49ers fear Isaac Guerendo suffered MCL injury, plus other updates

San Francisco 49ers running back Isaac Guerendo was forced to exit Sunday's game against the Arizona Cardinals during the first offensive drive. The rookie was carted off the field, and the team later announced he had sustained knee and ankle injuries, ruling him out for the remainder of the game.

Speaking to reporters after the game, head coach Kyle Shanahan shared the team's concern that Guerendo may have suffered an MCL injury.

"Not sure yet," Shanahan said. "Most likely an MCL, but we're going to have to find out for sure tomorrow."

Shanahan acknowledged the difficulty of losing Guerendo so early in the game. With only two other running backs suited up—Patrick Taylor, who stepped in for Guerendo, and fullback Kyle Juszczyk—the team was left thin at the position.

"It was tough, especially when you go out on a cart," Shanahan said. "I think that messed with everyone a little bit, but we're still holding out hope that it's good news, or good news in comparison to going off on a cart and everything. Hoping it's not an ACL."

Other injuries

Shanahan also provided updates on several other injuries:

• Safety Malik Mustapha sustained a cut and bruising to his knee and did not return.
• Safety Talanoa Hufanga left the game with a concussion and did not return.
• Cornerback Renardo Green exited with a groin injury and did not return.
• Tackle Colton McKivitz suffered an ankle injury and did not return.
• Wide receiver Chris Conley injured his elbow but returned to the game.