The Smashing Machine star Dwayne Johnson and writer-director Benny Safdie tried hard to tell the story of UFC fighter Mark Kerr truthfully — especially in the fight scenes.

The film follows Kerr, played by Johnson, as he rises in the ring but struggles with addiction outside of it as he tries to mask intense pain. Emily Blunt plays his long-suffering girlfriend, Dawn, who faces her own struggles.

The film has drawn Oscar talk for Johnson, previously best known for franchise and action films — and it’s safe to say he’s the only contender in this year’s Best Actor race who was willingly, as he describes it, “concussed” for his art.

In our cover story on The Smashing Machine, Johnson and Safdie told us that early in the making of the film, Safdie pitched the bold idea to always keep the cameras outside of the ring, and to avoid quick cuts and editing-assisted illusions.

“Benny and I were in a meeting, and he said, ‘I have something to pitch you. Tell me I’m crazy and I’ll never bring it up again: I would love to never cut away when you’re in the ring or in the cage.’” Johnson told writer Joshua Encinias.

“I said, ‘I would love that. I will train hard, and I will come in in the best, and hopefully decent, shape,’” Johnson recalled.

The most intense result of that approach came in a fight scene that recreates a famous brawl in Japan between Kerr and Kazuyuki Fujita, who is played in the film by actor and MMA fighter Yoko Hamamura.

Dwayne Johnson on Taking a Real Shot to the Face From Yoko Hamamura for The Smashing Machine

Johnson told Hamamura, literally, not to pull his punches.

“I pulled aside Yoko Hamamura,” Johnson recounted. “I said, ‘Hey, you have to hit me in the face.’ And he thought I was kidding. He goes, ‘No, no, I can’t do that.’ I said, ‘I mean it. I’m not trying to be a tough guy. You know what happened in this fight with Kerr and Fujita, and Benny’s not cutting away.’”

Safdie agreed: “I’m not going to cut away. I’m staying right there.”

Johnson insisted to Hamamura: “Please, please rock me. We got one shot with this. … You know how to hit. If you hit me here, I think you’re going to break my jaw. If you hit me up here, you’re going to break my cheekbone. If you could somehow… we get one shot at this, so rock me.’”

Hamamura did as he was asked, with predictably painful results. The fight appears prominently in the Smashing Machine trailer, which you can watch here if you can’t see it above.

“He f—ing rocked me so hard,” Johnson said. “It winds up in the trailer, where I’m up on my knees, and I’m wobbly and dazed. I was concussed and wobbly for days after that. But we didn’t cut away. And I’m glad we didn’t because that was a very pivotal fight for Mark that actually changed his life.

“Benny wouldn’t let us fake it,” Johnson added. “If Mark got rocked, I got rocked.”

Safdie and stunt coordinator Greg Rementer meticulously planned out every round and takedown, but there was no getting around the pain.

“There’s a level of respect for what these fighters go through. You can’t fake that. You have to feel it,” said Johnson.

Safdie elaborated: “Dwayne had to learn how to fight like Mark, to really make it feel believable. … That’s the first thing that takes you out of a movie like this — if you can just tell they’re not doing this stuff.”

The Smashing Machine is in theaters today, from A24.