Before the injury, which appeared to occur early in the Las Vegas Raiders' final drive of the first half, Watt had a strip sack of quarterback Derek Carr along with four tackles. Watt recorded his first strip sack against Josh Allen and the Buffalo Bills a week ago.
Prior to the season opener, Watt signed a four-year, $112 million extension that made him the highest-paid defender in the NFL. He didn't practice in the team periods for all of training camp and joined them for the first time four days before the Bills game.
Watt, 26, was the Steelers' fourth defensive starter sidelined by injury Sunday. Cornerback Joe Haden and linebacker Devin Bush were both inactive after suffering groin injuries that appeared on the injury report for the first time Friday.
Then in the first quarter, nose tackle Tyson Alualu went down with an ankle injury. He barely put any weight on his right ankle as he was helped off the field by Chase Claypool and Isaiah Buggs and, after an evaluation in the injury tent, was carted back to the locker room.