T.J. Watt's sudden lung issue freaked out a lot of people, including Steelers legend Brett "Da Beard" Keisel, who tells TMZ Sports he's hoping for a quick and full recovery so the defensive monster can return to the field ASAP!!
We spoke with the two-time Super Bowl champion this week ... shortly after Watt had surgery on his partially collapsed lung following a dry needling treatment at the Steelers' practice facility.
Watt -- former NFL Defensive Player of the Year -- will miss at least the December 15 "Monday Night Football" matchup .