by Patricia Sellers

New-product innovation tends to be 1% inspiration and 99% perspiration.

Here's that 1% that led to the creation of a hot little company called Sheex: One afternoon in the summer of 2007, Susan Walvius, then the head women's basketball coach at the University of South Carolina, was at practice and wearing a pair of over-sized, super-soft, performance-fabric shorts. "I'd love to have bedsheets made out of this stuff," Walvius said to Michelle Marciniak, her assistant coach.

"Let's do it," Marciniak replied.

The 99% perspiration: These two athletes took their idea--"performance bedding," if you can fathom that--and ran with it.

They lined up R&D help from the Darla Moore School of Business at USC.

They figured out how to apply to bedsheets the moisture-wicking and heat-transfer technology that Nike (NKE) and Under Armour (UA) use to make athletic clothing--and patented the technology for sheets and blankets.

They quit coaching last year. They raised $1 million from friends and family, picked a name, Sheex, and after hustling far and wide to find a manufacturer that could produce the high-tech fabric in the form of sheets and pillows, they contracted with a factory in California.

They started selling Sheex online in April. The tagline: "Sleep Better. Play Better." It appeals to professional athletes, weekend warriors, and--though Walvius and Marciniak would never say it--menopausal women.

In September, Fortune selected this duo to be among 10 Most Powerful Women Entrepreneurs--a new program that we recently launched with American Express (AXP). The Sheex founders and nine other honorees attended the Fortune Most Powerful Women Summit. There, Walvius, 45, and Marciniak, 36, appeared on an entrepreneurs panel along with SBA Administrator Karen Mills and Gilt Groupe CEO Susan Lyne.

Ever since, they have ferociously worked the network of MPWomen Summit participants--meeting with Allen & Co. investment banker Nancy Peretsman, Jones Apparel Group (JNY) COO Cindy DiPietrantonio, bank-industry analyst Meredith Whitney, and others. Today, I asked Marciniak how many nights in the past two months she and Walvius have been back home in South Carolina. "Three nights since September," she replied. "Six total since June."

They're constantly on the road, running their business from planes, trains, automobiles, and even buses. Constant hustle. Two weeks ago, in a meeting with Heidi Ueberroth, the NBA's head of global marketing partnerships, the Sheex women struck a game-changing deal to distribute their products in the NBA's flagship store in midtown Manhattan. That could lead to distribution on the NBA and WNBA websites and team sites and stores as well.

Full disclosure: I first met Walvius and Marciniak in July at the LPGA U.S. Open in Pennsylvania--and learned that Marciniak went to my high school, Allentown Central Catholic, where she was the top-ranked high school player in the nation. They called her "Spinderella" back then. She went on to play for the NCAA champion Lady Vols at the University of Tennessee, where she was MVP. I've come to know Marciniak and Walvius fairly well and have given them a few leads that have helped them with their business. It's important to acknowledge that, but it shouldn't detract from their achievement.

Here they are on video talking about their hustle to build Sheex--though as long as they're using their own product, I guess you'll never see them sweat.

P.S. Another window into Marciniak's raw ambition is a 1998 cover story in Sports Illustrated about her relationship with her former coach at the University of Tennessee, Pat Summitt--who today has more career wins than any other coach, woman or man, in NCAA basketball history.