Watch George Balanchine's "Agon," currently in splendid form at Pacific Northwest Ballet, and see a signature move that seems to symbolize exactly what the ballet meant at its debut 50 years ago. It's as if Mr. B saw a dancer in arabesque — that elegant classical line of one leg raised high — and gave his ankle a yank from behind, pulling the arabesque off-balance and the supporting foot back on its heel, with the toe up. In doing so, he not only created a beautiful diagonal shape but gave ballet itself a tug, moving it into new territory.

It's fitting that PNB's repertory evening "Contemporary Classics" begins with "Agon" and its twisty ampersands of movement, both as a nod to Balanchine and an off-kilter introduction to the dances that follow it. All are created by choreographers who move easily between the modern-dance and ballet worlds; all incorporate movement not necessarily learned in a ballet studio.

Susan Marshall's beautiful "Kiss," performed by two dancers suspended from the ceiling in harnesses, at times barely skims the floor, its dancers glide above it in wistful horizontal lines. Mara Vinson and James Moore create a slow, almost underwater language of yearning, reaching for each other even as they swing away. David Parsons' delightful "Caught," making its PNB premiere (it was performed earlier this year at Meany Hall by the Parsons Dance Company), plays with light and flight, catching a soloist in midair in the white glare of a strobe. Jonathan Porretta, who often dances as if his feet had wings, seemed effortlessly airborne. Never mind the flicking lights; you believed that he could fly.

Twyla Tharp's 1986 work "In the Upper Room," another PNB premiere, closed the evening with an energy that seemed to keep building, even as the curtain went down. Dressed in striped Norma Kamali costumes that resembled extremely chic prison uniforms (some of which would be stripped off to reveal tomato-red leotards), the 13 dancers seemed divided into two groups: the pointe-shoe group, who tossed off classical moves with abandon, and the sneakers group, who whirled and stomped with feet flexed and jogged with hands in loose fists between movements.

Set to a pulsating Philip Glass score at times flavored with tango and techno, the dance was a seamless flow of movement, with the dancers emerging from behind black curtains as if magically conjured there. Its cast (including the excellent Carrie Imler, a welcome sight after missing much of last season due to injury) seemed ready to dance all night; its moves a zesty duel of dance styles, with even a little soft-shoe tap thrown in. It's a playful, exuberant yank at ballet — just like "Agon" was, and is.

Moira Macdonald: 206-464-2725 or mmacdonald@seattletimes.com