T.J. Watt is being assessed by the Pittsburgh Steelers as reports suggest the reigning NFL Defensive Player of the Year has suffered a torn pectoral.

Watt left the game in the fourth quarter of the Steelers' wild 23-20 overtime win over the Cincinnati Bengals in Week 1.

The Pittsburgh pass-rusher had played a key role in stifling Bengals quarterback Joe Burrow, who finished with five turnovers – four interceptions and a lost fumble.

Watt dominated the game with six tackles, three tackles-for-loss, an interception and a sack, but the Steelers now fear he faces an extended period on the sideline.

"I'm appreciative of the effort – it wasn't without cost," said coach Mike Tomlin afterwards, revealing Watt was "being evaluated with an upper body injury".

Running back Najee Harris was also being evaluated having exited the game with a foot injury.