SAN DIEGO -- Morgan Fairchild and Bo Derek have been going at it for hours.

On an otherwise quiet Saturday night, there seems to be no end to the yelling, face slapping, hair pulling, tussling, and hurling of vases full of long-stemmed roses.

Then Fairchild grabs Derek by the throat as she gasps for air. The director yells "Cut!" We presume in a good way.

This sort of warring is typical on Stage 3 at Stu Segall Studios these days. Yet tonight, it's the mother of all cat fights. By 10 p.m., even assorted "antiques" and a couple of paintings have succumbed to the fury.

And some time around 4 a.m., it will all end deliciously in multiple layers of white butter cream as the raging rivals tumble into a towering wedding cake.

Just a taste of the melodramatic madness arriving Sept. 5 with the launch of MyNetworkTV, the Fox-owned upstart created for those WB and UPN affiliates left orphaned when their networks merged into a new venture known as The CW.

Each weeknight at 8 p.m. EDT, MyNetwork will present a pair of one-hour serials or "telenovelas" -- "Desire" (which follows the saga of two brothers in love with the same woman) and "Fashion House" (lots of beautiful women on the runway and others in fabulously staged cat fights). Other networks have similar projects in the works.

The MyNetwork shows will air Monday through Friday, with a recap episode on Saturdays, and conclude after 13 weeks, when a fresh pair of novelas will take their place.

Those shows are already in production at the Segall Studios -- "Watch Over Me," a dramatic love story a la "The Bodyguard" starring Casper Van Dien, and "Art of Betrayal," with Tatum O'Neal starring as a lover scorned.

"With the way that the world has been going, this is hitting exactly at the right moment," says Fairchild. "People are going to want to tuck the kids in and sit back and watch a couple of blondes bitch-slapping each other across the screen. What could be more fun than that?"

"It's insane," Derek says, noting the rigors of filming 65 episodes -- equivalent to three seasons of weekly shows -- in less than four months. "But my character is so much fun to play. She's just evil, and that's what intrigued me."

Adapted from the wildly popular Spanish-language genre, MyNetwork's telenovelas appear, at least for now, to lack the cultural depth and sexual passion of the originals.

But the shows will follow the same finite format -- self-contained stories with a beginning, middle and happily-ever-after end.

"What makes a novela unique is that there is an ending and a sense of urgency when you watch it because you know it's not going to be around forever," says Twentieth Television's programming chief Paul Buccieri.

"I've been a fan of this genre for nine years," Buccieri continues. "It was only until I was in this position that I could push this concept through."

Others have been doing some pushing of their own.

ABC's highly anticipated "Ugly Betty," inspired by the Colombian hit "Yo Soy Betty La Fea" ("I Am Betty the Ugly"), will air as a weekly, one-hour comedy beginning Thursday, Sept. 28.

CBS reportedly has at least four telenovelas in development from various producers.

And Galan Entertainment has inked deals with NBC Universal to create English-language versions of novelas produced by NBC's Spanish-language network, Telemundo.

Galan has also filmed the first mini-telenovela for cell-phone users, available through Cingular beginning next month.

If English-language novelas are successful, they could be in a position to take on the original Spanish-language market, which generates an estimated $2 billion a year worldwide, according to the trade publication Daily Variety.

"Hollywood executives are starting to pay attention to the ratings from Univision," says Buccieri about the leading Spanish-language network.

Last year, Univision beat every other network during prime time in the Spanish-language market's 18-39 demographic and "this summer, if you look at the top shows, eight out of the 10 are novelas," Buccieri says.

"It's sort of like comfort food," says Silvio Horta, executive producer of "Ugly Betty," which will go toe-to-toe with Univision's formidable Mexican version of "Betty," "La Fea Mas Bella," currently running Thursdays.

"My intention on this show," Horta says, "is to really give it a lot of heart and give it a lot of humor and people will hopefully hook into that." And the occasional cameo from executive producer Salma Hayek, a former novela star.

Although ABC's "Betty" was conceived as a weekly series, the network is exploring the traditional daily format in partnership with Mexico's Televisa.

"If telenovelas actually end up working for the Anglo market, it will open up the television industry to a tremendous area for growth," says Marcos Santana, who oversees program development for Telemundo.

Although there's a lot of corporate excitement about telenovelas, are American viewers ready for them?

"They will find a specific niche audience," says Julio Martinez, features editor and columnist for Latin Heat Magazine. "That is, if they like the story."

But, he adds, "the commitment from the studio has to be different. You can create five episodes of 'Ugly Betty,' throw it on the air and you're gambling on that amount of time for it to prove itself a hit or not worthy.

"When you commit to a telenovela, you're committed to 65 episodes (or more) upfront. There's no such thing as let's do the first five chapters of the book and see how it does."