Jay Leno,  Jimmy Fallon Jay Leno, Jimmy Fallon

Jay Leno returned to The Tonight Show Friday — and at times, it seemed like he forgot he was there as a guest rather than the host.

It was Leno's first appearance on the show since Jimmy Fallon took over hosting duties in February. And Leno made sure that Fallon and the audience knew which of the two of them had more life and business experience.

Shows on the Bubble: Which will survive?

When recalling car-shopping advice that he once gave Fallon, Leno compared Fallon's hand to "a puppy's paw." "He has never held a screwdriver or a wrench in his life," Leno said. "This is the hand of a 5-year-old."

It's clear that Leno is still smarting from his unceremonious dismissal by NBC. During an interview with guest Lucy Liu, Leno reminded Liu that he was her "first" (Tonight Show interview, that is). He also ribbed Fallon about being unfamiliar with Liu's show Elementary, which airs on CBS.

"I'm just loyal to my network," Fallon says. "I just watch things that are on NBC."

"Well, you have reason to be loyal," Leno shot back, to raucous laughter.

Leno also performed a six-minute stand-up set at the start of the show, and recalled his own first appearance on The Tonight Show. Watch the full episode here:

Leno won't be gone from late night for long. He will be Craig Ferguson's final guest on The Late Late Show on Dec. 19.