Will Smith keeps a chessboard handy on the set of NBC's "Fresh Prince of Bel Air." But like the character he plays, what he'd really like is a pool table.

Smith, a Grammy-winning rap singer known as Fresh Prince, frequently plays chess when he's not working on his new NBC comedy series. The show is his acting and television debut in the role of a tough street kid from Philadelphia sent to live with wealthy relatives in Bel Air.The comedy hinges on his attempts to adjust to the alien environment of wealth and excess, and to bring his relatives back in touch with their humbler roots.

The 21-year-old Smith's frequent chess opponent is Joe Marcell, who plays Geoffrey the butler as though he's just stepped out of "Masterpiece Theatre." They've also had a game on an episode of the comedy series.

"I play a lot of chess, but I don't know if I could say it's a passion," Smith says. "Pool is more of a passion with me. I put in a request for a pool table on the set."

Smith sees a similarity between himself and his character, also named Will Smith and nicknamed Fresh Prince. Smith also comes from the Philadelphia area and says he prefers not to fit in.

"I've never done any acting," he says. "I've never had any formal theatrical training whatsoever. I'm playing a character I designed five years ago for my rap concerts. It's pretty much a part of me now."

Smith, like his character, is a person who smoothes the way with incredible charm and an ability to think - and talk - fast. On the screen he seems at ease and natural, although his lack of training and experience occasionally surfaces in scenes with other cast members.

Prior to its premiere in September, NBC ballyhooed the show as its breakaway hit of the season. As often happens to highly touted young racehorses, it stumbled coming out of the gate.

Part of the problem may be that the audience apparently is not reacting well to Smith's making fun of middle-class values. As a result, some of the sharper edges of the humor are being honed down.

Among those hoping that Smith's "Fresh Prince" recording and stage performance success will transfer to a new audience is 20th Century Fox, which recently signed him for an action-adventure movie.

Smith picked up the nickname Prince in school. It has nothing to do with rock singer Prince.

"My eighth-grade teacher started calling me Prince and it sort of stuck," he says. "She did that because I was a pretty charming guy. I had a couple of different names. I don't remember all of them. When you're rapping you change your name every week trying to find one that fits. Once I was Willie Will. I settled on Prince in 1986, then I added Fresh because that's the new slang for cool.

"I was performing rap at parties by 1981 and getting paid for it. I always did rap. I play a little piano and guitar."

His rap partner was Jeff Townes, and by 1986 they had become D.J. Jazzy Jeff & the Fresh Prince. Their first single was "Girls Ain't Nothin' But Trouble," which they recorded on their own label and sold nearly 200,000 copies in Pennsylvania, Delaware and New Jersey. A major company picked it up and it became an international hit.

They've since recorded three albums, one of which sold 3 million copies. A fourth album is due out next year.

"Fresh Prince is not very different from Will Smith," he says. "He's fun-loving, mischievous and very handsome. He's just a sweet fellow. It's me, not a character. It's just me, rapping or acting.

"Rap is the only real musical art form we have in America now, other than jazz. You can listen to Elvis Presley and other stuff. It's all stolen from black Americans. Elvis is nothing but bits of Little Richard and Chuck Berry.

"Rap is more expressive and more individual. You have to write your own material because rap comes from the heart. I'd never sing anyone else's song."

Smith says the show is loosely based on the life of Benny Medina, a record company executive who is a co-producer of the series.

"He literally went from the streets to Beverly Hills High School in the span of a weekend," Smith says of Medina, who recommended that the "Fresh Prince" of rap music would be a natural TV character.

"He saw my music video and never considered anyone else," Smith says.