Gerard Butler attempted to avoid hospital treatment after an on-set surfing accident last month so he could continue filming his new movie.
The star was shooting "Of Men And Mavericks" in northern California when a large wave brought him crashing down, leaving him struggling to keep his head above the water.
Butler was taken to Stanford University Medical Center, but he had to be convinced by movie bosses to seek medical assistance.
He tells U.K. talk show host Graham Norton, "I was going to go back that day. I was actually in the ambulance and wanted to go back, which was a little crazy, but it's pretty addictive.
"This was maybe one of the few times that the reports were not exaggerated. It was a pretty close call... (The waves) just took me and I couldn't get up. It was pretty hairy."
But the incident helped Butler improve the portrayal of his character, surf enthusiast Rick 'Frosty' Hesson.
He adds, "In the movie, I put in a scene about a 'two wave hold down,' when you are down for so long that the next wave comes over before you get back up, and that's what happened to me. They finally grabbed me just as another huge wave was coming in. It was just like a movie! In fact, everything I talked about happening in the movie happened to me."