Trevor Siemian's return as an NFL starter lasted less than one half after he suffered an apparent leg injury in Monday's game against the Cleveland Browns.
Myles Garrett hit the New York Jets quarterback, causing an awkward landing and forcing him out of the game.
"The replay does not look good," Connor Hughes of The Athletic said. "This looks like a very, very serious injury."
Third-string quarterback Luke Falk entered the game to replace the injured player.
This article will be updated to provide more information on this story as it becomes available.