Muhammad Ali has been readmitted to hospital for follow-up care for a urinary tract infection, his second spell in the last four weeks.
Family spokesman Bob Gunnell said the three-time former heavyweight boxing champion was in a stable condition after being admitted to an undisclosed hospital earlier this week and is expected to be released today.
"There were still issues with the urinary tract infection," he said of the latest hospital stay.
Ali, 72, who has waged a long battle with Parkinson's disease, was admitted to hospital on December 20 with what was initially believed to be a mild case of pneumonia, but later turned out to be a severe urinary tract infection.
The man known worldwide for his boxing prowess and humanitarian work had been spending his time listening to music, reading and watching old films, Mr Gunnell said.
Mr Gunnell said Ali hoped to celebrate his 73rd birthday tomorrow with his family. He and his wife Lonnie have homes in Paradise Valley, Arizona; Berrien Springs, Michigan and in Louisville, Kentucky.
His birthday agenda is expected to include watching the Louisville-Duke men's college basketball game. Ali is a Louisville native and the Muhammad Ali Centre, which showcases Ali's humanitarian causes and boxing career, is a popular attraction in Kentucky's largest city.
Ali's public appearances have diminished in recent years but he still enjoys getting out and watching sports and visiting friends.
He retired from boxing in 1981 and devoted himself to social causes. He has travelled the world on humanitarian missions, mingling with the masses and rubbing shoulders with world leaders.