The Pittsburgh Steelers remain in the postseason mix, but they might be without their best player if they make it to the playoffs.
Rapoport added that Watt will undergo further testing to confirm the extent of the injury, but a Grade 3 MCL sprain is considered a multi-week injury, which would put his availability in question for next week's Super Wild Card Weekend were the Steelers to qualify.
Head coach Mike Tomlin did not provide an update or confirm the extent of Watt's injury following the game.
"T.J. is being evaluated with a knee injury," Tomlin told reporters. "I'll have more information probably the next time we get together. Obviously disappointed in that, but you know, there are challenges in the game of football. There are challenges in life. And so we'll deal with it, whatever it may be."
Pittsburgh (10-7) will secure a wild-card berth if the Jaguars or Bills lose on Sunday or Saturday's Titans-Colts game ends in a tie.
If the Steelers advance, it largely will be thanks to Watt's stellar play, which continued on Saturday against the Ravens as Watt recorded two sacks prior to his knee injury.
Watt will finish the 2023 regular season with 19 sacks, which currently leads the league and would give the six-time Pro Bowler his third career sack title if the numbers hold.
The last time he missed action due to injury, a seven-game stretch during the 2022 season, Pittsburgh struggled to a 1-6 record.
Following a big win but potentially an equally impactful loss, the Steelers will now have to await results from both the remainder of Week 18 and Watt's testing.