New England Patriots safety Devin McCourty exited Sunday's game against the New York Jets with a head injury, the team announced.
NESN's Doug Kyed speculated McCourty had suffered a concussion.
McCourty, 31, has been a staple of New England's defense since 2010 and one of the NFL's best free safeties in that time. He's a two-time Pro Bowler and two-time Super Bowl champion.
He notched 97 tackles and an interception in 2017, and he had 80 tackles and an interception through New England's first 15 games this season.
His injury is undoubtedly a blow for the Patriots, who have built a solid secondary with cornerbacks Stephon Gilmore and Eric Rowe joining the safety pair of McCourty and Patrick Chung.