Muhammad Ali released from the hospital for urinary infection

Ali, who has Parkinson's disease, was released from the undisclosed hospital in time to celebrate his 73rd birthday on Saturday, Gunnell said. He had been admitted to the hospital earlier this week as follow-up to a problem that surfaced last month.

"He's home and resting and glad to be out of the hospital," Gunnell said, adding that the Ali family "greatly appreciates the outpouring of support and continued well wishes."

The former three-time heavyweight world champion has been hospitalized twice in the past month.

Ali was first admitted on Dec. 20 with what was believed to be a mild case of pneumonia. Doctors, however, later determined he was actually suffering from a urinary tract infection, Gunnell said.

Ali, who is nicknamed "The Greatest" and the "Louisville Lip," retired from boxing in 1981 with a 56-5 record.