PHILADELPHIA -- Former heavyweight champion Joe Frazier is battling the liver cancer that has put him under hospice care.

The 67-year-old boxer sleeps for most the day but is coherent when awake, his personal and business manager said. Leslie Wolff, who has been the fighter's manager for seven years, said Frazier has been flooded with get-well messages from former boxers and fans.

Wolff told The Associated Press some fans have offered to donate a liver. A living person can donate a portion of his or her liver to another; over time, a donor's liver regenerates itself.

"There is evidence that there are certain people that fight much harder than other people, and in doing so, they last longer," Wolff said Monday. "They have the heart of a champion. Joe ain't no quitter. Even in this struggle, he's showing people you don't give up."

Frazier was diagnosed last month with the disease. His manager said the boxer had been in out and out of the hospital since early October and has been receiving hospice treatment the last week.

The documentary "Joe Frazier: When the Smoke Clears" will be screened Tuesday night at the DocNYC festival in New York.

"No matter what happens, we must make sure his legacy stays alive," Wolff said.

Wolff said doctors have not yet told Frazier how long he has to live. Wolff, who dismissed false reports all weekend that Frazier had died, denied a story that said he wanted to send Frazier to Russia for treatment. Wolff said he contacted doctors there only for ideas on other possible treatments.

"We just want to see what's out there to see what can be done here," he said.

Frazier was the first man to beat Muhammad Ali, knocking him down and taking a decision in the so-called Fight of the Century in 1971. He would go on to lose two more fights to Ali, including the epic "Thrilla in Manila" bout.

Frazier won the heavyweight title in 1970 by stopping Jimmy Ellis in the fifth round of their fight at Madison Square Garden. He defended it successfully four times before George Foreman knocked him down six times in the first two rounds to take the title from him in 1973. Frazier would never be heavyweight champion again.

Frazier has not allowed anyone to see him except immediate family and associates.

"He's in no shape to have any visitors, nor does he want any," Wolff said.

Information from The Associated Press was used in this report.