According to a poll done for "The Insider," the favorite host ever is Billy Crystal.
Does that mean Rock has a tough night ahead, The Early Show co-anchor Hannah Storm asked O'Brien.
"No question that Chris Rock is funny, but his comedy is often controversial," O'Brien said. "The organizers say his tryout is an experiment, but just in case he rocks the room with raw humor -- there will be a seven-second tape delay."
In a recent 60 minutes, Rock seemed OK with the idea of an instant censor.
"Chris Rock is a brilliant choice," O'Brien asserts. "The (nominated) movies are great, but they're not big blockbusters like 'Lord of the Rings.' So the buzz is about Chris Rock, who will bring an air of mystery the entire night."
O'Brien says Rock told him, 'I've been on television a lot without swearing and being salacious. And I'll be fine.'"
Storm also asked O'Brien about an interview "The Insider" landed with Mia Farrow, her first big interview in a decade.
"Mia tells us…that she's really moved on, if that's possible," O'Brien says. "You lose your adopted daughter, someone you tried to raise, to your live-in lover, and all of a sudden, (that lover) Woody Allen is marrying your adopted daughter. That's a tough one.
"She said life's too short and you have to move on, but can you imagine losing your daughter and having her get married in this situation?
"Mia says she may look fragile, but she says she is stronger than ever," O'Brien said. "Her longtime love affair with Allen hit the headlines in 1992, when he left Mia for her adopted daughter, Soon-Yi Previn. The public humiliation continued through a bitter custody battle, and Mia credits her other children with helping her move on with her life.
"Mia says that she actually removed Soon-Yi's place at the dinner table. She says it is easier to mourn her daughter's loss than to hold out hope every time the phone rings that Soon-Yi may be calling. In her mind, there will never be a reconciliation."
"The Insider" also spoke with Mia's and Allen's biological son, Seamus, who describes what it was like to watch his father romance his adopted sister.
Farrow just turned 60.
O'Brien also turned his attention to Las Vegas, where the MGM Grand is betting $16 million on, for an exclusive yearlong run.
"The 58-year-old tells us that playing just one theater allows him to launch his biggest production ever. And he's got so much music, he can change the show nightly and never run out of hits. But his most popular song might surprise you. It's Not "Mandy" or "Can't Smile Without You," but -- "Copacabana."