As Heidi Klum notes, there are times when the designers are in such a last-second panic, "They staple things together, you know? And then, the models have to pee and they're sewn into things, and they can't go to the bathroom. They're like, 'What should I do? I have to go to the bathroom.'"

This is the type of quandary that will be a part of "Models of the Runway," the new late-night companion series for "Project Runway" that will debut tonight (8/20) when "Project Runway" makes it much-anticipated premiere on Lifetime. It's all preceded by a two-hour special "All Star Challenge" with favorite designers of past seasons in a sort of sudden death competition, so it's a night ripe to satisfy the hunger of "Runway" fans.

According to Heidi, "We've been kind of playing with the idea of doing something with the models for awhile. And, it was great when we moved to Lifetime, and they said, 'You guys have to do something with the models.' There's so much great stuff that goes on backstage that nobody gets to see. The girls are great and working with the designers, a lot of drama goes on.

"We criticize and talk about the models as well, and how they can sometimes sell a garment if it is not made that well -- how they can help it out." The models give their views of the designers as well.

Then, there are the relationships among the girls, "the fights that they have and also the tears. They're young girls and they all live together, and they get sad when they start with 16 and get whittled down to the last three. They kind of become friends after awhile," says Heidi.

Having done her share of time on the catwalk, has the super model-cum-TV hostess ever had one of those moments of not being able to use the bathroom when the urge struck?

"Certainly. Absolutely," she answers. "Sometimes, when it's show time, it's show time. They're not going to hold the whole show for you when you have to go to the bathroom, so sometimes, you just have to be wonder woman and do things that normally you would do differently."

Gives sort of a new spin on those pained expressions models sometimes have out on the runway, doesn't it?