Affleck had been due to face off with his real-life best pal Matt Damon in "The Last Duel", featuring as former friends-turned-rivals, but the "Argo" star has since had to step aside due to scheduling issues.
Instead, he will appear in a supporting role, while Driver has been tapped to become one of the leads of the film, which is set in 14th century France, reports Variety.
The movie is based on Eric Jager's 2004 novel "The Last Duel: A True Story of Trial by Combat in Medieval France", which depicts the real-life battle between knight Jean de Carrouges and squire Jacques Le Gris.
It has been adapted by Affleck and Damon, who worked with writer/director Nicole Holofcener to give it the Hollywood treatment.
"The Last Duel" is expected to go into production in early 2020.