Stefano Pilati's influence has spread exponentially since his first YSL collection, the spring 2005 outing that—right off the bat—launched wide, waist-cinching belts and tulip skirts on the fashion world. Since those are the looks and proportions so many women are living in now, Pilati has become a force whose every subsequent move is analyzed for updates. This season, he articulated the next big shift likely to replace froufrou femininity. He's been thinking, he said, about "powerful clothes women might want to wear. A sort of versatile uniform."

Harder and sharper yet just as desirably luxurious, this collection steered more in the direction of the things Catherine Deneuve—not to mention Helmut Newton—enjoyed about YSL in the sixties and seventies: a point spelled out in the slick black PVC trench, leather blouse, maîtresse pinafore, form-encasing sequin cocktail dress and the odd suggestive mink pussy-cat bow that punctuated the show. (The fetish-chic elements offered a unique spin on "restraint," this season's buzzword.)

Pilati, however, was clever enough not to belabor the oft-repeated S&M mode to communicate his ideas about the new power woman. His most newsworthy contribution here was to make belted, form-fitting tunics, and back-buttoned tops look sexy—possibly for the first time ever. These are plain yet chic clothes (included among them, a shorter, sharper version of his tulip skirt) that can get you to work feeling fab. Yet there's more to Pilati's consideration of what women really want out of their wardrobe—and life—than a dutiful monolithic career suit. As he explained, "You can wear a tunic over narrow pants, with a skirt, or as a dress. And I've seen from watching my sisters how sexy it is to unbutton something at the back. You need a man to help." That's the sort of insight that will take a designer far.