Joe Frazier was known as one of the most elite fighters during the heyday of heavyweight championship boxing. His three bouts with Muhammad Ali—including the famed “Thrilla in Manilla” fight—helped solidify him as a legend, and his mean left hook became his trademark.

Now, the former heavyweight champ is in a fight for his life.

Frazier, who carried the nickname “Smokin’ Joe,” was diagnosed with liver cancer about four weeks ago, his personal and business manager Leslie Wolff told CNN. The 67-year-old is currently in a Philadelphia hospice. He is in the final stages of the disease. Leslie Wolff told the Associated Press that doctors have not yet told Frazier how long he has to live.

"He's a true gentleman," Wolff said. "Along with Muhammad Ali, [he is] one of the two most recognizable athletes in the world."

The son of a South Carolina sharecropper, Frazier won a gold medal at the 1964 Summer Olympics in Tokyo and went toe-to-toe with greats such as George Foreman, Oscar Bonavena, Joe Bugner and Jimmy Ellis. On Oct. 1, 1975, in the third match up between Frazier and Muhammad Ali, nicknamed “The Thrilla in Manila,” Frazier sparred with Ali for 14 rounds until his eyes were nearly swollen shut and his corner stopped the bout, according to the biography on the fighter’s website.

"It was the closest I've come to death," Ali said.

Frazier retired in 1974 only to stage an unsuccessful comeback attempt in 1981, after which he hung up the gloves for good.

Frazier’s fans took to Twitter over the weekend to send prayers and wishes for good health, including entertainer MC Hammer, who tweeted: “Praying for Smokin' Joe Frazier. He has the courage of 100 strong men in his heart.”

(Photo: Al Bello/GettyImages)