The 32-year-old actor is in negotiations to star as the lead in the boxing drama directed by Antoine Fuqua, reported Contactmusic.
If Gyllenhaal accepts the role offer, he will play a left-handed prizefighter, who wins a title but suffers a tragedy and is forced to put his life back together in order to earn the respect of his young daughter. The 41-year-old rapper was originally cast in the movie, but he reportedly bowed out after production struggled to get up and running.
Kurt Sutter is penning the script, which is set in a boxing ring, while The Weinstein Company is producing along with Riche Productions. Filming for 'Southpaw' is expected to kick off next year.