"How did he get that deal?" asked Leno. "We only got four months! Who's his agent?"
Still, Leno's jabs seemed less barbed than O'Brien's in the later time slot.
Wednesday, O'Brien seemed wholly uninterested in currying favor with NBC, and even took a swipe at his in-house rival.
"Hosting the 'Tonight Show' has been a fulfillment of a lifelong dream to me," he said. "I just want to say to the kids out there: 'You can do anything you want in life -- unless Jay Leno wants to do it too."
O'Brien's first guest of the evening, the dry-witted British comedian Ricky Gevais, got in on the fun too.
"You're having a good time sticking it to NBC aren't you," asked Gervais, who will be hosting the upcoming Golden Globe Awards for the network. "What are you going to do [next]? ... You've got no discernable skills."
Battle lines were drawn Tuesday afternoon, when O'Brien declared he will not do "The Tonight Show" if its new airtime is 12:05 a.m. After releasing his statement, fans rallied around O'Brien via the Internet, turning him into a trending topic on Twitter and voicing support for "Team Conan."
Below, the full text of O'Brien's statement.
People of Earth:
In the last few days, I've been getting a lot of sympathy calls, and I want to start by making it clear that no one should waste a second feeling sorry for me. For 17 years, I've been getting paid to do what I love most and, in a world with real problems, I've been absurdly lucky. That said, I've been suddenly put in a very public predicament and my bosses are demanding an immediate decision.
Six years ago, I signed a contract with NBC to take over "The Tonight Show" in June of 2009. Like a lot of us, I grew up watching Johnny Carson every night and the chance to one day sit in that chair has meant everything to me. I worked long and hard to get that opportunity, passed up far more lucrative offers, and since 2004 I have spent literally hundreds of hours thinking of ways to extend the franchise long into the future. It was my mistaken belief that, like my predecessor, I would have the benefit of some time and, just as important, some degree of ratings support from the prime-time schedule. Building a lasting audience at 11:30 is impossible without both.