There’s not much that’s tougher than a rock, but it seems Vin Diesel wanted to put that to the test. 

In a new interview with Men’s Health, the F9 star opened up about his relationship with franchise co-star Dwayne “The Rock” Johnson, and how things got so heated in their relationship. 

As Vin puts it, the pair clashed over what he’s referring to as a little method acting, which Uproxx initially reported. Basically, the actor was trying to get a good performance out of Johnson, but tension prevailed. 

“It was a tough character to embody, the Hobbs character,” Diesel shared. “My approach at the time was a lot of tough love to assist in getting that performance where it needed to be. As a producer to say, Okay, we’re going to take Dwayne Johnson, who’s associated with wrestling, and we’re going to force this cinematic world, audience members, to regard his character as someone that they don’t know–Hobbs hits you like a ton of bricks. That’s something that I’m proud of, that aesthetic. That took a lot of work. We had to get there and sometimes, at that time, I could give a lot of tough love. Not Felliniesque, but I would do anything I’d have to do in order to get performances in anything I’m producing.”

At the time, though, Dwayne was more than a wrestler. He had already appeared in several popular films, including Disney’s The Game Plan, as well as others like Walking Tall and The Scorpion King. Still, some speculate Vin’s comments mean Johnson’s potential return to the franchise and reuniting with his co-star. Even director Justin Lin claimed he had him in mind for the latest installment, so we’ll have to see where things go next. 

“On this one, when I came back, I was thinking a lot about Hobbs and Shaw, and all of the other characters,” he told CinemaBlend. “I never think of them as being gone, for sure.”