Paul Mescal is to replace Blake Jenner in 'Merrily We Roll Along'.
The 'Normal People' actor is to take on the lead role of Broadway composer Franklin Shepard in the musical movie, which will be directed by Richard Linklater.
According to The Hollywood Reporter, the film will shoot over 20 years.
Stephen Sondheim provided the music and lyrics for the 1980s musical, which is based on the 1934 play of the same name by George S. Kaufman and Moss Hart.
The musical tells the story of three pals and how their friendship changes over 20 years.
It mainly focuses on Shepard, who ditches his pals to become a Hollywood movie producer, and the story moves backwards in time from 1976.
Last week, it was revealed Mescal is set to star in Sir Ridley Scott's 'Gladiator' sequel.
He is said to be in talks to take on the leading role of Lucius Verus, the son of Roman Empress Lucilla and the nephew of the villainous Commodus, who was played by Joaquin Phoenix in the original movie.
David Scarpa is writing the script, while Ridley will produce alongside Michael Pruss via Scott Free, and Doug Wick and Lucy Fisher via Red Wagon Entertainment.
The sequel is set to start filming in Ouarzazate, Morocco in May and it is hoped original star Russell Crowe will make an appearance in flashbacks as his character Maximus from the original 2000 epic.
The first movie - which also starred Derek Jacobi, and the late Oliver Reed in his final role - won five Academy Awards, including the coveted Best Picture accolade and Best Actor for Russell, as well as a string of other gongs including BAFTAs and Golden Globes.