Christian Kirk hurt his groin on the first play for the Jacksonville Jaguars in Monday night's game against the Cincinnati Bengals.
Quarterback Trevor Lawrence picked off Kirk on a 26-yard pass and the wide receiver was wide open when he jumped up and took the catch.
But he landed awkwardly and lay there, rolling in pain before eventually staggering off the field and back to the locker room.
He was listed as questionable to return with concerns about a muscle injury.
The Jags then scored a touchdown on the drive through Travis Etienne to take an early lead in the game.
But a significant injury to Kirk would be a major blow to the Jaguars, who have continued to improve as the NFL season has progressed.
The team lost two of the first three games of the season, against the Kansas City Chiefs and Houston Texans, before winning seven of the next eight.
The team leads the AFC South with an 8-3 record on Monday Night Football.
Incredibly, this is the first time since 2011 that the Jaguars have played Monday Night Football.