Can man hold his own against machine? So far, he seems to be doing just fine.
The score so far: Brad Rutter and Watson tied in first place with $5,000 each; Ken Jennings stuck in third with $2,000.
Although Watson made a strong showing in the beginning, it stumbled later in the contest with the more complex questions.
When asked for the decade in which Oreos were introduced, Watson incorrectly answered: "What is the 1920s?" after Jennings already provided the same incorrect response.
Later, Watson flubbed again when host Alex Trebek offered the clue: "Stylish elegance, or students who all graduated in the same year."
The computer replied: "What is chic?"
But the correct answer, provided by Rutter, was: "What is class?"
For the past four years, top artificial intelligence researchers at IBM have been preparing their mega-machine, Watson, to compete on "Jeopardy!" against all-time champions Jennings and Rutter.
The much-hyped three-day matchup between man and machine, which was taped in January, aired on national television for the first time Monday night and continues until Wednesday.
Watson Plays at a Very High Level, Jennings Said
In an interview with ABCNews.com last week, Jennings said the pressure is on.
"One of the first things I thought was, 'This time, I'm not just playing to pay my mortgage or something, or to feed my kid's college fund, I'm actually sort of representing 7 billion human beings against our new machine tyrants,'" he quipped. "That was a lot of responsibility. I didn't want to let people down."
When "Jeopardy!" first called him a couple of years ago to let him know that IBM was working on a supreme game-show machine, Jennings said he was "skeptical."
As a former computer programmer himself, he said, he knew the computer's limitations and doubted if IBM actually could pull it off.
But when he watched taped matches of Watson playing against top human contestants, he realized that beating the computer was hardly a foregone conclusion.
"Clearly, it was playing at a very high level. It sort of effortlessly handled the kinds of things I thought computers couldn't do," he said. "It could understand wordplay, it could understand things that were more conceptual than a single fact."
But when the machine gets something wrong, Jennings said, "it gets it spectacularly wrong."
For example, Jennings said an IBM developer told him that when asked for the Russian word for "goodbye," Watson gave the answer "cholesterol."
"To me, that's just crazy," he said. "There's no way a human player could duplicate that kind of mistake, but Watson has no idea. It just doesn't have all the checks and balances we do."
Rutter: Humanity Wins Even If Man Loses
Still, Rutter said, despite its mistakes, Watson is a very powerful computer.
"I think humans will be surprised," he told ABCNews.com. "Especially because it's just "Jeopardy!" clues like you see every day on the show. To see a computer actually figuring it out, with all the little twists and turns and puns that they like to get in there, even factoring those in. To see how well Watson is doing, I think might scare some people."
Potentially anticipating the sci-fi-fueled "eventual robot takeover of society," Rutter said IBM has been emphasizing that Watson is an "it" and not a "he."
"I think they sense that people will get freaked out by how well it's doing and how well it can approximate a human," he said.
But regardless of whether Rutter, Jennings or Watson wins the match, Rutter said, no one really loses.
"Ken and I are representing humanity in this thing but, at the same time, Watson was developed, built, programmed by human beings," said Rutter. "So I think humanity wins no matter what happens."
And beyond even that, Jennings said that playing the world's most sophisticated computer gave him a new appreciation for the humble human brain.
"I was impressed at the end that the human brain -- just a few dollars worth of water and salt and protein and whatever else we have in our skulls -- that that could hang in there and play at the same level as this jillion-dollar computer the size of a room," he said. "It says a lot for the human brain that with what we have we can hang with the world's most powerful computer. It's sort of a newfound respect for what our heads can do, which we take for granted sometimes."
The Associated Press contributed to the report.