By Will Robinson
Updated May 20, 2016 at 12:00 PM EDT
  • Movie

Edgar Ramirez and Usher may be playing fighters on opposite sides of the ring in Hands of Stone, but when it came to getting in shape for the Roberto Duran biopic, they were in it together.

“These guys, they put themselves through — literally — hell in preparation for these fights,” Usher, who plays Sugar Ray Leonard, told EW at the Cannes Film Festival. “The first thing [Ramirez and I] connected on was, ‘How are you losing the weight, how are you holding it?'”

Ramirez, starring as Duran, said his strategy involved following the paleo diet and “eating like a caveman, pretty much.”

Playing Duran’s trainer Ray Arcel in the movie is Robert De Niro, who endured an intense physical transformation for his Oscar-winning boxing epic, Raging Bull; he commended Ramirez and Usher’s effort.

“It’s murder when you’re try to stay in shape and keep your weight down,” De Niro said. “I thought they were great.”

See the clip above. Hands of Stone opens in theaters on Aug. 26.

Hands of Stone

  • Movie
  • R
  • 105 minutes
  • Jonathan Jakubowicz