San Francisco 49ers wideout Brandon Aiyuk’s season went from bad to worse.

Late in the first half of a 28-18 loss to the Kansas City Chiefs, Aiyuk caught a pass over the middle. He was hit and his knee buckled. Aiyuk stayed down the field. Finally he left the field and entered the medical tent. At halftime he was carted to the locker room. The 49ers shut him out shortly after halftime.

After the game, 49ers head coach Kyle Shanahan said the team feared Aiyuk had suffered an ACL injury.

Aiyuk held out for most of the offseason and preseason despite plenty of trade speculation surrounding him, then signed a four-year, $120 million contract to remain with the 49ers.

He got off to a slow start, with just 351 yards and no touchdowns in six games. Also on Sunday, Aiyuk dropped a long pass in the first half.

Aiyuk is the latest major injury for San Francisco. Christian McCaffrey hasn’t played all season. First-round draft pick Ricky Pearsall didn’t make his NFL debut until Sunday after being shot in the chest before the start of the season. Deebo Samuel Sr. played just a few snaps on Sunday before leaving the game due to illness.

The 49ers have gotten off to a slow start this season, due in part to injuries. The demise of Aiyuk will not help.