NEW YORK (CNN/Money) - Giving away a billion dollars isn't monkey business. But for Pepsi and one very lucky game-show contestant, it just might be a job for a chimp.

The soda maker's widely publicized "Play for a Billion" sweepstakes will end on Sept. 14. That night, the WB Network will air a live special, hosted by comic Drew Carey, in which the finalists in Pepsi's summertime promotion have a slim chance to win $1 billion.

If the money is won, that would be by far the biggest prize in the history of game shows, not to mention soda-pop ad campaigns. But if anyone is to claim the cash, a 4 ½ year-old chimpanzee named Kendall will be responsible.

Smile, Kendall, it's your big break.

The contest has worked like this: Numbers were printed inside the caps of about 1 billion containers of Pepsi products. To play, consumers registered and submitted numbers on the game's Web site. Via weekly drawings, Pepsi selected 1,000 people who will be flown to Orlando to appear on the TV show.

Just before the program begins, each player will get an individual six-digit number. In the opening minutes of the show, 10 numbers will be picked, and those who hold them will become the game's finalists.

The 10 will play successive, numbers-based games of chance. After progressive elimination, a single person will win a guaranteed $1 million prize. In order to become a billionaire, that person's number must exactly match another six-digit number to be drawn at random.

Kendall the chimp will do the drawing.

Throughout the summer, Pepsi has promoted the contest with in-store displays, an e-mail campaign, advertising on the WB, and all manner of marketing hype. The company spent an estimated $15 million to do so.

Some 4 million people registered to enter the contest, according to Pepsi spokesman David DeCecco, making it the company's biggest online promotion to date.

"Consumers are bombarded with so many messages, it's hard to get their attention – our goal was to break through the clutter," said DeCecco. "Giving away a potential $1 billion certainly grabs people's attention."

Besides host Carey, the Sept. 14 show will feature comedian Jamie Kennedy, actress Holly Robinson Peete, and Kendall, who will appear in the role of "Mr. Moneybags."

Although Kendall's air time will be relatively limited -- his big moment comes at the end -- he may steal the show.

"He has incredible charisma, a real joie de vivre," says Jennifer Henderson of Birds & Animals Unlimited, the Orlando-based animal training company Kendall calls home.

The chimp was selected after a nationwide search produced dozens of star-struck simians. Kendall's audition tape, Henderson said, "showed him doing a wide range of behaviors he might be called upon to perform during the show."

The producers discovered Kendall somewhat late in the process. They were so impressed with him, however, they gave him the job instead of another chimp, who was already appearing in ads promoting the show.

(That animal could not be reached for comment, but Pepsi's DeCecco claims there were no hard feelings. "It's show biz," he said. "Roles get re-cast all the time.")

"The special is a great platform to launch our new season with," says the WB's Keith Marden. A large audience for the Pepsi event would give the network's other programs – which will be promoted to the hilt during the special -- a viewership boost.

Although the contest is open to people of all ages, Pepsi's choice of the WB as a partner is a sign that the campaign is particularly geared toward a youthful crowd, the prime audience for most of the network's programs. (Note: the WB, like CNN/Money, is owned by AOL/Time Warner.)

Whether the campaign will ultimately be viewed as a success won't be known until after the special airs, when ratings are in -- and Kendall's dexterity has been demonstrated.

If the chimp does pick the right number, Pepsi (PEP: Research, Estimates) would be thrilled, because the promotional value of a billion-dollar payout would be inestimable.

Even better, the prize money would come from Warren Buffett's Berkshire Hathaway (BRK.A: Research, Estimates), which has assumed the risk of a payout in return for a seven-figure insurance premium.

If it is forced to pay, it will be a bad day not just for Buffett, but also for Pepsi's biggest rival.

That's because Berkshire, among other things, is the largest shareholder in Coca-Cola (KO: Research, Estimates).