Matt Damon has praised his Irish co-star Cillian Murphy's performance in the upcoming "Oppenheimer," saying that the three-hour film was "fantastic."

“It’s three hours. It’s fantastic,” Damon told Variety about Christopher Nolan's latest Murphy-fronted film.

“Cillian is phenomenal. He’s everything you would want him to be,” Damon said.

“I think it’s almost three hours. It goes so fast, it’s great.”

Damon, who plays Leslie Groves in "Oppenheimer," was speaking at the premiere of "Air," the Ben Affleck-directed feature about Michael Jordan and the creation of Nike's Air Jordan sneakers. In the movie, which opens on April 5, Damon plays Nike sales agent Sonny Velasco.

Matt Damon has seen #Oppenheimer: "It's fantastic. It's three hours. Cillian [Murphy] is everything you'd want him to be. He is phenomenal."

— Variety (@Variety) March 28, 2023

In "Oppenheimer," Cork native Cillian Murphy takes on the titular role of theoretical physicist J. Robert Oppenheimer, the director of the Manhattan Project and the “father of the atomic bomb.”

According to Variety, the film is Nolan’s first at Universal Pictures after a long run at Warner Bros. The script is based on Kai Bird’s biography “American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer” and focuses on Oppenheimer’s research effort as the Los Alamos Laboratory director.

At three hours, “Oppenheimer” exceeds the runtime of Nolan's two longest films. His 2014 sci-fi pic “Interstellar" had a run time of 169 minutes, while 2012's  “The Dark Knight Rises" ran for 165 minutes.

Alongside Murphy, the cast of "Oppenheimer" also includes Belfast native Kenneth Branagh, Emily Blunt, Florence Pugh, Robert Downey Jr., Rami Malek, Benny Safdie, Josh Hartnett, Dane DeHaan, Jack Quaid, Matthew Modine, Alden Ehrenreich, David Krumholtz, and Michael Angarano.

“Oppenheimer" opens in theaters on July 21.

You can watch the trailer for "Oppenheimer" here: