Conan O'Brien making 'Tonight Show' debut

First night's guests include Will Ferrell, Pearl Jam

NEW YORK -- Conan O'Brien debuts as "Tonight" show host Monday, taking over television's most historic late-night franchise in a transition five years in the making.

The network built a new studio for O'Brien, who is moving West after hosting NBC's "Late Night" in New York. O'Brien expects much of his comedy in the early going will reflect the lanky, red-haired personality's move from an East Coast culture to California.

Will Ferrell, who made several memorable visits to O'Brien's "Late Night," will be the first guest. Pearl Jam is the musical act.

The "Tonight" show provided late-night television's blueprint, and has thrived through the years with Steve Allen, Jack Paar, Johnny Carson and Jay Leno. Leno inherited a first-place show, lost ground to David Letterman for a few years, but returned to the top and has remained there for more than a decade. He joked on his last show that the feat allows him to get his security deposit back.

Letterman is still at CBS to provide O'Brien with competition, along with a resurgent "Nightline" and Jimmy Kimmel on ABC and Stephen Colbert on Comedy Central. Between a multitude of cable stations and lists of recorded programs on DVRs, O'Brien faces a challenge for attention.

Leno -- who will continue on the NBC schedule with a prime-time comedy hour five nights a week beginning in September -- drew 16.1 million viewers for his 1993 debut and was averaging 5.2 million viewers this season, according to Nielsen Media Research.

NBC had announced in 2004 that O'Brien would take over this job, keeping him at the network when there was a risk he might leave without a promised promotion.

O'Brien and NBC were tamping down expectations initially, refusing to let reporters see his show in advance of its airing on the East Coast.

"I'm not going to cure cancer on the first show, and I'm not going to jump Snake River Canyon. I'm not going to levitate. Sometimes people forget this is the first show of what I hope will be many, many, many shows," O'Brien recently told the Associated Press.