It's inevitable that Z Zegna would ride out this week in the shadow of its elder brother, Ermenegildo Zegna. Stefano Pilati's return to fashion at the latter was the subject of the season.

There are some clear connections between E and Z Zegna, chief among them the resources of the Lanificio Zegna, the family's production facility, to draw upon. But while Pilati's first collection updated the sometime stodgy traditionalism of the flagship label, it maintained a quiet respect for tradition. Not so at Z. Paul Surridge has always been nearly fearless about adapting and evolving, often faster than the speed of comfort. His stranger experiments have a Future World sheen. Here, he set about updating eveningwear. He developed technical wool, mohair and taffeta blends, and cottons, the result of which was to make the most refined menswear there is look unexpectedly sporty: His trousers, inspired by pajamas, amounted to formal track pants. There's a crisp efficiency to even his most sinuous lines, from the elongated tuxedo jackets (shown with high-neck knits, not shirts) to the squared-off shirttails floating, untucked, under jackets or knits.

To give credit where credit is due: If it didn't have the propeller force of newsiness its counterpart did, Z Zegna did have a bracing novelty all its own.