"Amateur, my butt!" exclaimed host Maria Menounos.

Country star Blake Shelton simply bowed.

And the audience gave a standing O.

Philadelphia's Patti LaBelle and the singers she selected from the city apparently knocked it out of the park last night on NBC's new reality TV competition, Clash of the Choirs.

The show, which continues tonight and tomorrow and concludes Thursday, pits chorale groups handpicked by five stars in their home cities. Nick Lachey's Cincinnati group tugged heartstrings with a backstory about a father and daughter who auditioned to honor their mother, who has cancer.

Michael Bolton's singers hail from New Haven, Conn., Shelton's from Oklahoma, and Kelly Rowland's from Houston.

At stake are not only bragging rights but a top prize of $250,000 for local charities. LaBelle's group is competing for the Abramson Cancer Center of the University of Pennsylvania and its With Our Voices program, which focuses on breast cancer.

In the show's segment about LaBelle, she explained that breast cancer had touched her family.

She held her local auditions at Philadelphia International Records, where the legendary Kenneth Gamble and Leon Huff produced a remarkable string of hits.

"Some of the best singers in the world recorded here, and I have to prove I'm the best," she said, speaking of her competitors on the show.

A string of auditioners seemed intimidated - even tongue-tied - in her presence.

Clearly, her patience was sorely tested.

"If anybody had done 'Lady Marmalade' any more, I was gonna slap 'em," she said.

Her wide-brimmed hat came in handy when she couldn't help but laugh.

She'd lean the hat down and fan herself with her hand.

When one singer heard her snickering, she kindly said: "I laugh when I'm happy."

But eventually she did find 20 talented singers.

"I'm gonna work them so hard, they're gonna think they're in boot camp," she declared.

Competing last on the show, her choir delivered a rousing "He's Got the Whole Word in His Hands." A pair of women performed lead vocals, and sections traded off with rousing call-and-response riffs, and, of course, the occasional "Hallelujah!"

"Wow! Wow! I am speechless!" said Menounos.

"I feel all good!" said LaBelle.

Tonight, viewers will find out which groups stay.

The other groups performed well, too, but unless America is the Land of Tin Ears and Leaden Hearts, LaBelle and company will be back ... if not headed for a recording contract.

For more information, including video clips, go to http://www.nbc.com/Clash_of_the_Choirs.

Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.