PITTSBURGH -- The Steelers could be without one of their primary offensive players for their biggest game of the season.
Tight end Ladarius Green is under concussion protocol and meeting with Dr. Micky Collins of University of Pittsburgh Medical Center for evaluation.
The Steelers (9-5) are preparing to face the Baltimore Ravens (8-6) in a Christmas Day clash at Heinz Field that will likely decide the AFC North.
Green has emerged as the No. 2 option in the passing game, with at least 65 receiving yards in three of his past four games.
Steelers coach Mike Tomlin said the team will "follow the protocol to the letter."
"Whatever they say, we do," Tomlin said.
Players under the concussion protocol will be tested every day, either in a lab or with physical activity, Tomlin said.
Green, who signed a four-year, $20 million contract in March, had at least one documented concussion in 2015 as a member of the San Diego Chargers.
Green missed the first nine games of 2016 with an ankle injury. NFL Network reported in August that Green was suffering from recurring headaches, though Tomlin and Green have maintained he missed game action solely for the ankle.
Tight end Jesse James would likely see an increased role in the passing game if Green is out.
In other injury news, defensive end Stephon Tuitt has a sprained knee, which could leave Pittsburgh thin on the defensive line. Tomlin said Tuitt is rehabbing now and has a chance to play, in part because his position doesn't require heavy open-field cutting.
Tuitt's potential absence would leave Pittsburgh with four healthy linemen on the 53-man roster -- L.T. Walton, Dan McCullers, Javon Hargrave and Ricardo Mathews, who's battling an ankle injury.
"I want to see where [Tuitt's] rehab takes us and put together a plan accordingly," Tomlin said.
Running back DeAngelo Williams didn't play last week in Cincinnati after experiencing knee swelling. Wide receiver Darrius Heyward-Bey (midfoot), who got hurt against Baltimore in Week 9, has begun running full speed in a straight line and has a chance to play this week. Linebacker Anthony Chickillo has an ankle injury.