Ben Stiller will replace Mark Ruffalo in "Greenburg," a dramedy written and directed by Noah Baumbach, according to the Hollywood Reporter.

No official reasons have been given to explain Ruffalo's exit. The trade says Amy Adams, who was originally expected to star alongside Ruffalo, also had to drop the project.

Plot details are strictly kept under wraps, although the story may focus on relationships between characters similar to those of Baumbach's previous flicks.

Baumbach earned an Oscar nomination for "The Squid and the Whale." He most recently directed "Margot at the Wedding," and he also wrote the script for Wes Anderson's "The Fantastic Mr. Fox."

Stiller, who was last seen in "Tropic Thunder," will next star in "Night at the Museum 2: Battle of the Smithsonian."