In the often high-stakes ratings game of late night television, the hosts have learned: It helps to have a few loyal guests to call your own.
When Conan O'Brien made the move to Los Angeles to become the host of "The Tonight Show" last week, he called on his good friend and ally Will Ferrell, who was also his last guest on the final "Late Night with Conan O'Brien" show in New York last February.
These two go back to their days at 30 Rockefeller Center, where Ferrell got his break as a "Saturday Night Live" cast member and O'Brien broadcast his late night talk show. Ferrell, a frequent guest, would usually strip off his pants whenever he appeared on "Late Night."
Not so for O'Brien's "Tonight Show" debut last Monday. Ferrell, wearing a pin-striped suit, made his entrance to the set on a platform carried by four men dressed like Egyptian guards from "The Ten Commandments" movie. But once he was on the couch, the two comedians returned to their familiar rapport.
"No one thought you could do it, not one person," said Ferrell, on the show to promote his new movie, "Land of the Lost." "And you're here."
Ferrell's appearance, along with rock group Pearl Jam, was enough to knock O'Brien's premiere out of the park. The show earned an overnight 7.1 in the ratings, the highest-rated Monday episode of the franchise in four years, according to The Hollywood Reporter.
And even though the ratings shrank with each successive episode, O'Brien still carried the week against David Letterman's "Late Show."
But by Tuesday night, Letterman had closed the gap and overtaken "The Tonight" Show with a 3.4 rating to NBC's 2.9.
Maybe Letterman's loyal friend Howard Stern is part of the reason. Stern came out fighting on Monday when Letterman had him on as a guest. Stern, no friend of Jay Leno's, dissed the former "Tonight Show" host while praising Letterman.
On Monday, Howard Stern proved his loyalty to David Letterman by praising the "Late Show" host and dissing his longtime competitor Leno.
"I never liked Jay. I can't stand Jay," Stern said. "I've never seen anybody who behaves like a robot like this guy. I watched his final show, saying goodbye to the 'Tonight Show,' reading it off a teleprompter for crying out loud. Where's the emotion? Where's the humanity?"
Pointing at Letterman, Stern then shouted, "Here's the host that we want to watch."
The audience cheered, the band played and Stern danced a little jig. Letterman, who smiled throughout Stern's tirade, sat back in his chair as if to take in the praise, then said, "Thank you, Howard."
Stern also rallied Letterman and the audience against O'Brien.
"This Conan O'Brien took over the Leno show. You heard about this?" Stern asked to laughter. "We got to beat this Conan. For God's sake, how are you feeling? Jay left late night television and now you've got this new guy to compete with?"
Stern even confessed his loyal allegiance to Letterman.
"I've got to say something about loyalty. Dave put me on national television many, many years ago before I was known, and I have stuck with Dave," said Stern, whose first "Late Show" appearance in 1984 helped launch the original shock jock and his radio show into the national spotlight.
Stern's not the only one. When Letterman was nearly on death's doorstep with a severely constricted heart and quintuple by-pass surgery, his loyal guests, including Barrymore and Roberts, introduced re-runs of the show.
When Roberts made her return to the limelight this spring while promoting her film "Duplicity," she stopped by Letterman's set. And, as she has done before, Roberts teased Letterman about his unwed status with his longtime girlfriend Regina Lasko and mother of his son Harry Joseph. Is it just coincidence that he tied the knot with Lasko two days later?
One guest it took Letterman 16 years to woo to his couch and a decided Leno loyalist was Oprah Winfrey.
Winfrey first appeared on "The Tonight Show" in 1985 when Johnny Carson was still king and before she was talk-show queen.
She got Carson's attention for hosting "AM Chicago" a local talk show that was beating Phil Donahue. As Winfrey's star grew brighter over the years, she returned many times to the "Tonight Show" couch, but seemed to snub Letterman's invitations -- leading to rumors that there was a feud between Winfrey and Letterman.
His much-maligned joke when he was the Academy Awards host in 1995 -- the awkward "Oprah, Uma. Uma, Oprah" introduction -- didn't help. Nor did making Winfrey the frequent target of jokes on his show. In 2003, Winfrey told Time magazine she wouldn't go on his show because she was "completely uncomfortable" with the jokes.
But two years later, in a massive buildup to the show, Winfrey appeared on Letterman's stage ready to bury the hatchet, though both wondered how the supposed feud started in the first place.
"Could you tell me please what has transpired?" Winfrey asked Letterman during the show. "I have never for a moment had a feud with you."
Still, Winfrey has shown a clear preference for Leno, as has comedian Jerry Seinfeld, who recently advised Leno's successor: "The 'Tonight Show' should always feel like the headquarters for show business."
Maybe that's why some stars prefer it.