LOS ANGELES, Calif. – Willie Nelson, Merle Haggard and Kris Kristofferson shared the Staples Center stage Friday as they rehearsed for the Grammy Awards — a trio of legends, right? Not in Kristofferson’s mind.

“I have to pinch myself,” the amiable 77-year-old Texan said after the practice session. “When I’m up there singing, I think: ‘I gotta be dreaming this.’ Because they’re my heroes. And they’re also my friends!

“They treat me with respect — like I’m one of them. But I remember who I really am.”

Along with triple Grammy nominee and “The Voice” star Blake Shelton, the trio sang a winning medley that included Haggard’s “Okie From Muskogee” and “Mammas Don’t Let Your Babies Grow Up to Be Cowboys,” popularized by Nelson and Waylon Jennings.

Jennings, Nelson, Kristofferson and Johnny Cash once comprised the outlaw country supergroup the Highwaymen, who recorded three albums together including a platinum-selling self-titled debut.

Kristofferson now jokes “it was great just being on Willie’s bus.” But he immediately shifts back into a state of reverence when discussing his old friend further.

“I can’t think of anybody other than Hank Williams who’s in my mind in the class of Willie and Merle,” said a smiling Kristofferson, his white hair and goatee neatly styled.

“I’ve always really respected both of them. All the serious songwriters in Nashville from the time I got out of the army idolized both of them, because they were the real thing. They were the closest thing to Hank Williams and they still are.”

Kristofferson, an experienced screen actor as well, is a three-time Grammy winner, an Academy Award nominee, a Golden Globe winner and a member of the Country Music Hall of Fame.

His last record — the self-released “Feeling Mortal” — came out just last year. But the former athlete (he was actually once featured as a cross-disciplinary up-and-comer in Sports Illustrated) acknowledges that he isn’t quite as sharp as he once was.

“I had brain damage back when I was playing football. Too many concussions and knockouts,” he said. “The memory’s gone. But I can still play the guitar and sing my own songs.

“And I can sing with these guys, ’cause they’re like brothers. For me, this is like a dream to be up there and treated as an equal. They might as well have Hank Williams out there and Ray Charles. … They all respect me? Oh, boy.”