The buzz is that Foxx, who looks uncannily likes Charles in the film, will take home Oscar gold for his performance as the great blind artist.
"The 36-year-old actor is winning raves for his portrayal of the genius behind classics such as 'What'd I Say' and 'Georgia On My Mind,'" writes The Associated Press's Anthony Breznican, characterizing Foxx's performance as "electric."
To prepare for his role, Foxx wore prosthetics over his eyes to understand how it feels not to have sight.
"You get angry because you can't see," Foxx told FOX News. "You want to take them off, but you have to keep them on. I had to keep them on during lunch, so I couldn't see for 12 to 14 hours a day."
Foxx previously has been known for comedic and supporting roles, as well as his keen impersonations of Mike Tyson, Bill Cosby and even Ronald Reagan. And he gave a standout performance earlier this year in "Collateral," which also starred Tom Cruise.
But Foxx's Oscar could be threatened by the script for the film. An early review in New York magazine says that while Foxx rocks, the clunky screenplay may undermine him. The film has to open big and win over audiences to push the ordinary dialogue under the carpet, the review predicts.
In the film, Charles is followed from his days as a boy learning to play piano after going blind at age 7 to a superstar who achieved worldwide fame.
"Ray" hits both high and low notes in Charles' personal life, touching on his promiscuity and drug addiction as well as his ability to overcome his disability and rise to the top.
Charles was involved in the making of the film before he died earlier this year, ultimately giving it — and Foxx — his blessing. But the music legend made sure the movie star was worthy of the role.
"The first thing he said was, 'Let me check these fingers out,'" Foxx told the New York Post. "He's like, 'Oh, you got strong fingers. Oh yeah.'"
Foxx actually wanted to be a pianist when he was a child, and made money playing for cocktail parties and his church choir. But Charles wasn't convinced the star was the right choice for the film.
"Ray really put Jamie through the paces," the film's director Taylor Hackford told the Post. "He was pretty rough on him."
In one of the hoops he made Foxx jump through, Charles asked the comedian to play the piano with him. The actor kept up at first, but a tricky bebop tune by Thelonious Monk (search) stumped him.
Luckily, Foxx figured it out in only 15 minutes. When he did, Charles was ecstatic.
"He said, 'This is it. This is the kid. He's got it!'" Hackford told the Post. "Ray himself anointed Jamie at that point."
Foxx is passionate in his conviction that Charles' story is an inspiring one that needs to be told.
"In 50 to 60 years, have you ever seen another Ray Charles?" Foxx told FOX News. "That's how you know he's special. In 50 or 60 years, you can't point to anybody else like him. That's how you know he's rare."
FOX News' Catherine Donaldson-Evans, Lisa Bernhard, Bill McCuddy and The Associated Press contributed to this report.