Boxing legend Muhammad Ali is back in the hospital, this time for a urinary tract infection, a publicist for the former pugilist said Thursday.

Ali, who turns 73 on Saturday, was said to be in stable condition and is expected to be released Friday.

No other details, including the hospital where Ali was staying, were immediately released.

Ali was hospitalized late last month with a mild case of pneumonia, and was released last week.

He was diagnosed with Parkinson's syndrome in 1984, three years after his retirement. He's since traveled the world on humanitarian missions, mingling with the masses and rubbing elbows with world leaders. Ali received the Presidential Medal of Freedom from President George W. Bush in 2005.

This past September, Ali attended a ceremony in his hometown of Louisville for the Muhammad Ali Humanitarian Awards. He did not speak. He also attended the University of Louisville's Oct. 30 football game against Florida State.

The Associated Press contributed to this report.