His long-term prognosis was not immediately clear.
Any time missed by Watt is a big blow for the Steelers. The runner-up for NFL Defensive Player of the Year last season, Watt was off to a hot start to 2021 prior to his injury. He recorded two sacks in Pittsburgh's season-opening win over the Buffalo Bills and sacked the Raiders' Derek Carr once on Sunday prior to leaving the game.
Watt, 26, led the NFL in sacks with 15 in 2020. He recorded 14.5 sacks in 2019 and 13 in 2018. A two-time All-Pro and three time Pro Bowler, Watt is critical to a Steelers team anchored by its defense. He signed a four-year extension worth about $112 million earlier this month to make him the NFL's highest-paid defensive player.