A new trailer for Concussion has hit the web, focusing more on Will Smith’s performance as Dr. Bennet Omalu, who linked the disease chronic traumatic encephalopathy (CTE) with American football.

Omalu’s pursuit to get the NFL to admit that there was a dangerous link between playing the game and the disease is the subject of the film. Smith plays Omalu as a man who struggled with his own identity as an outsider who tried to make a change to something Americans love.

Sony had to defend the film in September when leaked emails appeared to show that the studio made changes to the script, fearing that the NFL wouldn’t like it. But Sony called those reports “misleading.” The first trailer was released in August.

Concussion is based on the GQ story “Game Brain” by Jeanne Marie Laskas and was written and directed by Peter Landesman (Parkland).

In addition to Smith, the film stars Luke Wilson, Alec Baldwin, Gugu Mbatha-Raw, Albert Brooks and Paul Reiser. Ridley Scott is a co-producer on the film.

Concussion opens on Dec. 25.