At the age of nineteen, Hedlund made his debut in his first feature film playing Patroclus who was the younger cousin of Achilles played by Brad Pitt in the mythological epic adventure war drama "Troy", directed by Wolfgang Petersen. The film was released on May 14, 2004. He also co-starred with Billy Bob Thornton, Amber Heard and Tim McGraw as Don Billingsley in the 2004 sports drama "Friday Night Lights", where McGraw played his abusive father. He co-starred with Mark Wahlberg in the crime drama "Four Brothers" as Jack Mercer.