Thousands of mourners will pay final respects to Muhammad Ali on Thursday and Friday. Among those flocking to funerals in the Champ’s hometown of Louisville, Ky., will be former Post writer and longtime Ali insider Michael Marley.

A self-described “latchkey kid” from Boston, Marley started an Ali fan club in 1961. Three years later, he tracked the champ down at the Statler Hilton.

Marley tells The Post’s Michael Kaplan: “I was 12 years old, had been stalking Ali by mail and got him on the phone in his hotel room. He asked if I was white or colored. I told him, ‘I’m colored white.’ He laughed and said, ‘You’re funny, kid.’ I snuck out of seventh grade the next day and met Ali with Malcolm X and Louis Farrakhan. Then, a few months later, I was with him in his dressing room for the famous one-punch knockout of Sonny Liston” — which took a mere 90 seconds.

“Everybody, except for Ali, was shocked by the knockout,” Marley recalls.

Eventually, Marley was brought in as the youngest member of Ali’s 60-person entourage. “He had one guy driving girls in from the airport and another one driving them back out. He had a witch doctor who came up with ‘Float like a butterfly, sting like a bee.’” He remembers watching exploitation films with the boxer at a Times Square grindhouse, listening to the Rolling Stones and shooting baskets in an empty Madison Square Garden.

“He threw nothing but air balls,” says Marley. “Ali was a horrible athlete but the world’s greatest boxer.”