The San Francisco 49ers are "worried" Brandon Aiyuk suffered an ACL injury during Sunday's 28-18 loss to the Kansas City Chiefs, head coach Kyle Shanahan told reporters postgame.
Shanahan added that an ACL injury is not confirmed, but the team will know more Monday after running tests.
Aiyuk was injured on a 15-yard reception just before halftime when Kansas City defensive back Chamarri Conner came in for a tackle that forced the WR's knee to bend back awkwardly.
He remained on the ground receiving medical attention for several minutes before going to the sideline and eventually being carted to the locker room.
Before his departure, Aiyuk had collected 23 yards on two catches.
The 49ers deemed him out for the rest of the contest in the middle of a third-quarter drive that would bring them within two points of the Chiefs, 14-12. Following that possession, San Francisco also ruled out wide receiver Deebo Samuel, who had played just three snaps, due to an illness.
Those losses piled up, and Kansas City would eventually pull away to open up a two-score lead.
Without Aiyuk and Samuel for the duration of the second half, tight end George Kittle stepped up to finish with a team-high 92 receiving yards on six catches and rookie WR Jacob Cowing logged his first two career catches, contributing 50 yards.
The defeat moves San Francisco to 3-4 on a season which appears to be on unsteady ground. A prolonged loss of Aiyuk, who has gotten off to a slow start with 25 catches for 371 yards but remains a key piece for the 49ers, will make turning things around several degrees more difficult.
Next up, the Niners host the Dallas Cowboys on Sunday Night Football in Week 8.
