Kansas City receiver Rashee Rice left the field on a cart with a knee injury Sunday after a bizarre play in which he was hit by Chiefs quarterback Patrick Mahomes while both players were pursuing Los Angeles Chargers cornerback Kristian Fulton during an interception return.
Rice was declared out for the rest of the game after the first quarter ended with the Chiefs trailing 10-0.
After the 17-10 win, Rice was feared to have suffered a torn ACL, ESPN's Adam Schefter reported, citing sources.
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Rice is set to undergo further testing Monday to confirm the diagnosis.
Chiefs head coach Andy Reid spoke to media after the game and said he feels "terrible" for Rice as they don't expect to receive positive news, but "will hope for the best."
Mahomes overthrew Travis Kelce at midfield on the Chiefs' second drive, and Fulton returned his interception 29 yards with 6:06 to play. Rice caught Fulton from behind at the Chiefs 20 and punched the ball loose for a fumble — but Mahomes hit Rice's legs while the star quarterback ducked down to attempt a tackle on Fulton.
Chiefs center Creed Humphrey recovered the fumble, but video review revealed Rice had been out of bounds when he forced the fumble, allowing the Chargers to retain possession.
Both of Rice's knees took an impact in his collision with Mahomes, and the receiver's right knee appeared to hyperextend.
Rice is the defending Super Bowl champions' leading receiver with 24 catches for 288 yards and two touchdowns, ranking third in the NFL in receptions entering Week 4. No other Chiefs receiver has more than nine catches this season.
Rice is awaiting trial on several charges after he allegedly caused a high-speed crash involving multiple cars last March on a freeway in Texas.