49ers fear WR Brandon Aiyuk tore right ACL in loss to Chiefs

SANTA CLARA, Calif. -- The San Francisco 49ers fear that wide receiver Brandon Aiyuk tore his right ACL on Sunday, according to coach Kyle Shanahan, but he will undergo more tests to confirm the injury.

Aiyuk was injured with 48 seconds left in the second quarter of San Francisco's 28-18 loss to the Kansas City Chiefs . Niners quarterback Brock Purdy found Aiyuk between two Chiefs defenders for a gain of 15 yards. Chiefs defensive backs Chamarri Conner and Trent McDuffie converged on Aiyuk as he took a low hit, leaving his knee in a precarious position.

Aiyuk stayed down as Niners medical personnel came out to help before he was able to get up, slowly limp to the sideline and head to the medical tent. He went to the locker room soon after, and a return was ruled out as the third quarter opened.

The injury to Aiyuk comes after fellow receiver Deebo Samuel came down with an illness Sunday morning. Samuel didn't do much in warmups, and the team announced that he was sick but expected to play.

Samuel walked onto the field just before the game started and participated in the coin toss but was moving slowly. He did not have a catch or carry before he was eventually ruled out for the rest of the game.

Entering Sunday, San Francisco was already missing Jauan Jennings , who suffered a hip injury in last week's win against the Seattle Seahawks .

Without their top three receivers, the 49ers were down to veterans Chris Conley and Ronnie Bell and a pair of rookies, Ricky Pearsall and Jacob Cowing .

Pearsall, the No. 31 pick in April's NFL draft, was playing in his first regular-season game 50 days after he was shot in the chest during an alleged robbery attempt.