Vanessa Williams, <EM>A Capitol Fourth</EM> Vanessa Williams, A Capitol Fourth

Of all the leading men in the multimedia career of Vanessa Williams, Kevin Clash is by far the least recognized.

In fact, this strappingly handsome, soft-spoken and unassuming African-American gentleman may be the most famous anonymous star in the celebrity universe. For Clash, a puppeteer since his childhood in Baltimore, provides the voice and movements for Elmo, Sesame Street's stringy red ambassador of mirth and frequent collaborator with the divine Ms. Williams.

On the night of July 4, Williams and Elmo will perform a duet during A Capitol Fourth, the annual PBS music-and-fireworks spectacular broadcast from Washington (check local listings). Jason Alexander will host this year's brassy extravaganza, featuring Stevie Wonder, Jo Dee Messina, Michael Bolton, the National Symphony and, yes, the crouching, heard-but-not-seen Kevin Clash, who, as Elmo, will lead the nation in singing a rousing chorus of "Happy Birthday" to the U.S.A.

"Kevin is a consummate pro," says Williams of her friend and sometimes singing partner. "He's got great ideas, he's funny, he's warm, and, amazingly, he always hits the notes in an octave higher than anyone else sings. Working with him  and Elmo  is a no-lose situation."

The duo will perform "How Do You Do?" a composition written by the late, legendary Sesame Street songwriter Joe Raposo and first performed on the children's program by Lena Horne and Grover, back in the Carter administration. "Hey, if the song was good enough for Lena, it's good enough for me," Williams says with a chuckle.

Williams and Clash first worked together during the filming of The Adventures of Elmo in Grouchland, the preschool romp that cast the soul diva as the Queen of Trash. Though the reviews were mixed for the feature, there were no quibbles with Elmo's acting abilities or the over-the-top performance by Williams, whose cinema credits range from Soul Food to Shaft.

Since Grouchland, Williams and Clash have clicked. In 2005 they appeared at the annual fund-raising gala for Sesame Workshop (formerly Children's Television Workshop), the nonprofit production company that is responsible for Sesame Street. Williams says that their in-the-moment timing in that performance  and her ability to suspend her sense of disbelief and treat the puppet as a living being  comes from experience with her four children when they were Elmo's "age."

"You connect with Elmo the same way you would with a 2-year-old," she says. "As a parent, you muster that same kind of enthusiasm trying to explain something to your preschooler.

"My kids have grown up with Elmo, and Kevin," she says. "In my living room, we have a picture of Elmo with my now-13-year-old son. It's a part of what I call my Wall of Fame."

All told, as leading men go, Williams says the puppeteer providing the helium-high voice of Elmo is a stand-up guy, even when he's hunkered below her.