Veteran cinematographer Rachel Morrison, who is making her feature-film directing debut with “The Fire Inside,” introduced the film at TIFF as “a labor of love beyond my wildest imagination.”

The film, written by Barry Jenkins (“Moonlight”), who was also a producer, had its world premiere at the Toronto International Film Festival Sept. 7.

It is based on the true story of Claressa “T-Rex” Shields, a female boxer from Flynt, Mich., who won gold medals at the 2012 and 2016 Olympic Games. Shields’s enthusiasm as a child compelled her coach, Jason Crutchfield, to welcome her into a boxing class that was only open to boys. Crutchfield becomes more than a coach; he becomes a major influence in her life, supporting her through her unstable relationship with her mother and her difficult financial situation.

Newcomer, Ryan Destiny, who plays Shields, captures the boxer’s strength and determination, as well as her vulnerability. Brian Tyree Henry gives a nuanced performance as Crutchfield, a coach full of human warmth, and the two have excellent chemistry.

Shields and Crutchfield joined the cast and filmmakers for a Q&A after the screening. When asked what it was like seeing her life on screen, Shields replied “It’s very surreal. I don’t know if you guys could tell, but I cried my eyes out. You guys did such a great job.

“It was very moving and motivating,” Shields continued. “It’s different. But I’m happy that the world gets to see my story. It made me understand how I am, the way that I am, and why I’m the greatest woman of all time,” receiving thunderous applause from the audience.

Asked about the training process, Destiny noted “It was extremely exhausting. I had absolutely no background in boxing whatsoever, so it was a very different world for me. I trained with Rob Sale, who’s the main boxing trainer and weight trained as well, and it was constant for months. That was before the pandemic, and then we stopped, and then I had to do it all over again.”

She continued, “It was me also studying Claressa’s exact movement, which is very specific to her. She is a one-of-a-kind fighter, and I’m really, really blessed and happy that she thought I did such a good job.”

Henry, who’s  getting awards buzz for his performance in the film, had nothing but praise for his co-star: “Ryan really, really gave her all, and it was unbelievable and a testimony to just how powerful [she is].”

The film realistically depicts the struggles of the female boxer after winning the gold medal when she was only 17 in the second half of the film, rather than ending with their victory, as is often the case in sports films.

The issue of gender equality among athletes has been a popular topic recently, and Shields has long been an advocate for equal pay and equal opportunity for female boxers. The fact that Shields failed to receive a single commercial endorsement following her gold medal win, is in itself an indication of the plight of female athletes and especially women of color.

As a cinematographer, Morrison’s credits include “Fruitvale Station,” “Black Panther,” and “Mudbound,” for which she was the first woman to be nominated for an Academy Award for cinematography. She has also directed several television series, including “American Crime Story” and “The Mandalorian.”