The NFL and NFL Players Association are jointly reviewing T.J. Watt's concussion and the protocol after the Pittsburgh Steelers defender entered the protocol a day after taking a hard hit early in the team's Thursday night loss to the New England Patriots, according to a league source.

Watt entered the league's concussion protocol Friday morning after he arrived at the Steelers' practice facility and reported concussion symptoms.

Watt was hit in the face by running back Ezekiel Elliott's knee on the first play of the game. He missed just two plays before returning to the field.

The review, which is standard when a player enters the protocol, will involve a review of video and medical report, as well as interviews with Watt, the Steelers' medical staff and independent medical staff.