Robert Pattinson and Tom Holland became worried on the set of “The Odyssey” when they hit their star, Matt Damon, screaming over and over in his trailer. Was Damon suffering? Or have an explosive fight over the phone? Pattinson had questions and then discovered that Damon was simply muffling his voice so he could sound older like the battle-weary Odysseus in Christopher Nolan’s epic.

“Matt was in the trailer next to me and he was making these noises,” Pattinson said during an MTV UK video interview. “He’s such a nice guy… I thought he was on the phone and I thought he was a complete psychopath. He was just screaming and screaming and screaming. I thought he was having a really bad experience in the bathroom. He was just muffling his voice just to look older. Like you’re really taking years off your life by doing this.”

Holland also heard Damon’s screams and called his prep work “unbelievable.” Oscar nominee Damon is completely transformed in “The Odyssey.” He revealed on the “New Heights” podcast earlier this year that he dropped his weight to 167 pounds for the film.

“I lost a lot of weight. [Nolan] “He wanted me thin but strong,” Damon said. “Just because of this other thing I did with my doctor, I stopped eating gluten. I used to walk between 185 and 200, and I did the whole movie at 167. And I haven’t been this light since high school. So it was a lot of training and a very strict diet.”

It’s a far cry from when Damon had to gain weight for his characters. The Oscar nominee gained 30 pounds for 2009’s “The Informant” by “eating like crazy and drinking dark beer,” he told EW at the time. “In between meals on set, I would have a number one value meal at McDonald’s and then Doritos on top. It was absolute heaven.”

“The Odyssey” opens in theaters on July 17 from Universal Pictures.