(Reuters) - Three-time Defensive Player of the Year J.J. Watt has undergone a back surgery and could be in doubt for the Houston Texans’ season opener, the NFL reported Thursday on its website.

Watt will begin training camp on the physically unable to perform list and the timeline for his recovery is unclear, making him doubtful for Houston’s Week One tilt against the Chicago Bears on Sept. 11.

Watt, 27, is widely considered the top defensive player in the NFL and has never missed a game during his stellar five-year career at defensive end.

A four-time Pro Bowler, Watt led the league in sacks last season with 17 1/2 and helped the Texans finish atop the South Division.

But he also played through various injuries, including a herniated disk in his back.

(Writing by Jahmal Corner in Los Angeles; Editing by Amlan Chakraborty)