Anyone who has eagerly followed Gael Garcia Bernal since his breakthrough roles in “Amores Perros” and “Y tu mamá también” likely never foresaw him one day in the world of lucha libra wrestling.

Bernal, far from the most brawny actor, has been a slyer shape-shifter, whether in heels as a femme fatale in Pedro Almodovar’s “Bad Education” or on a motorcycle as Che Guevara in Walter Salles’ “Motorcycle Diaries.”

But while almost anything with Bernal in it has been worth seeing, it’s been a little while — maybe his pair of movies with Pablo Larrain, 2012’s “No” and 2016’s “Neruda” — since Bernal had a sufficiently good part to, well, really go to the mat for.

He’s found it, though, in “Cassandro,” Roger Ross Williams’ based-on-a-true-story drama about the Mexican wrestler Saúl Armendáriz. He was an exótico in 1990s lucha libra wrestling who rose to become one of the sport’s most popular champions.

Exóticos, who first emerged in the 1940s, evolved to be male fighters dressed in drag who served as a contrast to the macho main events. But Armendáriz, a gay man, wanted his character, Cassandro, to be more than that. He wanted to spar with luchadores on equal ground.

“Cassandro,” which opens in limited theaters Friday and debuts Sept. 22 on Amazon Prime Video, follows Armendáriz’ rise from scrawny outsider to center stage. The odds are always against him, but Bernal plays Armendáriz with an infectious innocence, even when he’s doing lines in the bathroom. Most of all, his transformation of the exótico into something more than is prescribed by luchador tradition makes for a stirring metaphor of gay empowerment.

Armendáriz, after struggling to catch on as the wrestler El Topo, is convinced by his trainer (Roberta Colindrez) to jump into the ring as an exótico. Armendáriz, though, has no interest in playing Cassandro as he’s supposed to. For starters, he wants to win, and exóticos were intended to to be fey, flamboyant victims for the hulking luchadores to easily dispatch.

They were also masked, but Armendáriz chooses to go without — an especially bold move considering the withering waves of homophobia directed at him by many in the crowd. But Armendáriz wins them over, and in doing so, achieves something spectacular, turning a gay stereotype into a hero. “I felt like Wonder Woman,” the real Armendáriz once said.

“Cassandro,” which co-stars Bad Bunny, doesn’t always make time for some of the inner pain that Armendáriz was experiencing. (He dealt with depression and drug addiction.) And the filmmaking by Williams, in the narrative debut for the longtime documentarian, can be muddled. The story is so sensational that you almost wish “Cassandro” was instead a feature-length documentary. (Williams first made a fine short about Armendáriz for the New Yorker in “The Man Without a Mask.” )

Yet “Cassandro” will surely bring many more to Armendáriz’s remarkable tale. Bernal, again channeling the feminine side he showed in Almodovar’s “Bad Education,” makes up for what he lacks in physical strength with charm. It’s a terrific performance, even if it doesn’t measure up to Cassandro’s.

“Cassandro,” an Amazon Studios release, is rated R by the Motion Picture Association for language, drug use and sexual content. Running time: 107 minutes. Three stars out of four.