T.J. Watt, the 2021 NFL defensive player of the year, is in the midst of another strong season with 14 sacks through 13 games.

Watt's sack total is second in the NFL, one behind league leader Khalil Mack's 15. 

Earlier this week, Watt reported concussion-like symptoms to the Pittsburgh Steelers' medical staff. 

The team placed the 29-year-old pass rusher in concussion protocol. Watt told team doctors about his symptoms Friday, one day after the New England Patriots upset the Steelers

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T.J. Watt in action during a Steelers game

T.J. Watt of the Pittsburgh Steelers during a game against the San Francisco 49ers at Acrisure Stadium Sept. 10, 2023, in Pittsburgh.  (Joe Sargent/Getty Images)

Watt exited Thursday night’s game in the first quarter after taking an inadvertent knee to the face mask from Patriots running back Ezekiel Elliott.

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Watt spent a brief period on the sideline before returning, recording five tackles while playing 51 of Pittsburgh’s 57 defensive snaps. He was held without a sack for the third time in 13 games.

T.J. Watt during warmups

T.J. Watt of the Pittsburgh Steelers warms up prior to a game against the Indianapolis Colts at Lucas Oil Stadium Nov. 28, 2022, in Indianapolis. (Justin Casterline/Getty Images)

Alex Highsmith, who with Watt forms one of the most formidable pass rush tandems in the NFL, missed most of the loss to New England after entering the concussion protocol in the first quarter.

Pittsburgh’s linebacker corps has been ravaged by injuries this season. Inside linebackers Kwon Alexander and Cole Holcomb are already out for the year, and Elandon Roberts played against the Patriots despite a groin injury.

TJ Watt celebrates after a first quarter sack

Pittsburgh linebacker T.J. Watt (90) celebrates after a first-quarter sack against the Baltimore Ravens at M&T Bank Stadium Jan. 9, 2022, in Baltimore.  (Randy Litzinger/Icon Sportswire via Getty Images)

The Steelers have limited options at outside linebacker, with rookie Nick Herbig and veteran Markus Golden the only players on the active roster with outside linebacker experience.

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Thursday's second straight loss hurt the Steelers' playoff hopes. The Steelers will have a couple extra days of rest before they take on the surging Indianapolis Colts Dec. 16.

The Associated Press contributed to this report.