Jaeden Lieberher is taking big steps in acting

"His performance is nuts," an admiring Bill Murray says of his "St. Vincent" co-star, Jaeden Lieberher, who was 10 when he showed up in Sheepshead Bay, Brooklyn, last year to work with Murray — and Melissa McCarthy, Naomi Watts, and Chris O'Dowd.

"He's self-composed," Murray adds, "and he responded brilliantly."

As for Lieberher, who grew up in South Philadelphia and moved to Los Angeles three years ago, working with Murray, he says, was "nerve-wracking at first — but then I got comfortable with him."

He was already a huge fan of "Ghostbusters" and "Groundhog Day."

Lieberher and his mother, Angie Martell, didn't move west with the idea of getting into show business, he says, "but people told me I should try out."

He did, landing the plum gig of the kid who rounds up his buds to beat a squad of bullies in that Hyundai Santa Fe Super Bowl ad. Other commercials followed.

It took six auditions to get the part of Oliver in "St. Vincent."

After watching the wide-eyed grade-schooler for a few days on set, Murray recommended Lieberher to filmmaker Cameron Crowe. Crowe's project, still untitled, was shot in Hawaii and stars Bradley Cooper, Rachel McAdams, Emma Stone — and Murray. Lieberher plays McAdams' son.

From there, Lieberher moved on to New Orleans, to Jeff Nichols' "Midnight Special," about a father and his son on the run. His co-stars: Kirsten Dunst, Michael Shannon, Joel Edgerton, and Adam Driver.

Lieberher, whose dad, Wes, runs a food truck in L.A., says the toughest scene he had in "St. Vincent" was near the film's end: a school presentation, an auditorium full of kids and extras and his castmates, all looking on.

"I had to memorize four pages of a speech and do it in front of hundreds of people," he says on the phone from L.A. "But then Bill helped me out. We meditated together, and he taught me how to relax."

He meditated with Bill Murray? That's even cooler than acting with him.