Moss, who was nominated for a Tony Award for her portrayal of Heidi Holland in the 2015 revival of The Heidi Chronicles, will play Wepner's second wife, Phyllis, whom he was with when he fought his famous 15-round fight against Muhammad Ali in 1975. She is joined by Schreiber as Chuck Wepner and Watts as his third wife, Linda.
In Wepner's most famous fight, Ali won in a technical knockout. Wepner is said to have read for a role in "Rocky II," but was not cast. "Rocky III" is thought to be based on one of his fights.
Schreiber and Mike Tollin will co-produce. Philippe Falardeau, Jeff Feurzeig, Jeff Stahl and Michael Cristofer will write the screenplay.