No, they just gotta dance-still. And judging from opening night in Austin, Texas, last week, they’re still peerless. Tharp has always been an entrancing performer as well as the greatest modern-dance choreographer since Graham. Over the years her dances for Baryshnikov, especially the 1976 ballet “Push Comes to Shove,” helped turn a dazzling, Soviet-trained classicist into the most brilliant dancer of his time. Their very names conjure excitement: nearly every performance on the tour is already sold out, and reportedly each star will walk (or limp) offstage at the end with more than $1 million. Both are working with sharply diminished powers nowadays, but each is blessed with an extraordinary theatrical charisma that age and injuries haven’t touched. When the curtain came down on opening night-after a program with none of the gorgeous pyrotechnics that made Baryshnikov famous and little of the physical daring that has long characterized Tharp’s work-the audience jumped to its feet and a huge ovation swept the theater.

For this tour Tharp has choreographed an evening-length work called “Cutting Up.” Backed up by an ad-hoc company of 10 young dancers, most of whom have been gleaned from ballet companies and pop music, the two stars explore why and how people dance-sometimes looking glamorous indeed and other times looking like the workaday drudges that dancers really are. Act I is “Schtick,” a dozen quick takes on styles ranging from ballet to Bob Fosse. Act II is “Bare Bones,” the essence of the art: Tharp and Baryshnikov and the 18th-century sinfonias of Pergolesi. The last section is “Food,” and it’s full of the dances people do when they crave movement-social dancing, complete with a Baryshnikov Charleston. This survey starts with a 1917 tea dance set in the Palm Court and culminates in a wild display of air kissing and subliterate chic at Mortons, the L.A. hot spot.

Even now, nobody moves like Tharp. Gently sliding and loping and spinning, dropping to the floor and bounding up in a single breath, her head tilted and her arms out; she rests so securely in the music we never see an attack, we only see the flow of movement. In a few spots she’s up to some of her old tricks: a bout of dizzy-limbed eccentric dancing to Louis Armstrong’s “Whosit” and a hilarious evocation of “Three Little Fishes” with a crew of men holding her as she plunges and dives and flaps. These moments are wonderful, but the truth is, she commands a stage beautifully just by walking out in her sweats, swigging from an Evian bottle and noodling around to a little music.

There are no duets here for Tharp and Baryshnikov; what she’s made are solos. Some they do together, like mirror images, and some they do alone, but all evening they never touch; they barely acknowledge one another. The first number they share is set to Hoagy Carmichael’s “I Get Along Without You Very Well.” Possibly this means they hate each other (Tharp won’t talk to the press about him, and Baryshnikov won’t talk to the press at all). But the two have been friends for years. More plausibly, Tharp looked hard at the situation-two stars, one stage-and made a characteristic decision to be entirely literal about sharing the spotlight. When they are together, they are virtually the same dancer; when they’re apart, they’re themselves.

Unfortunately, Baryshnikov doesn’t do very well noodling around in sweats. He wasn’t much good in the movies, and he isn’t much good swigging Evian; he has to move. In the Pergolesi section he seems to brighten as soon as the music starts. Tharp has choreographed this for his amazing delicacy, his flawless classical line, his perfectly attuned rhythm and the still-matchless beauty of his bearing. As a result, he’s breathtaking. But his role in the Pergolesi has another dimension, too, a truly startling one that emerges slowly into full focus. He does a big spin, but it goes off balance, a tilt-a-whirl. He throws us a huge, gaping grin, drops to the floor in a pose from “Le Corsaire,” strikes another famous pose from “L’Apres-midi d’un faune” and another from “The Sleeping Beauty.” Then, with a sweet smile, he exits. It’s a portrait gallery of Russian dance, especially the roles of Nijinsky-the noblest dancer of his day, whose career was cut short when he went mad. Baryshnikov’s next moment onstage is brief: he falters, he staggers as if strobe lights are pounding him and he flees.

This chilling vignette is one of the most stirring dances ever made for Baryshnikov, in his prime or out of it. Other sections of “Cutting Up” show him off handsomely, but here Tharp is affirmed once more as his greatest sculptor and Baryshnikov proves once more that he remains her greatest material. Sure, they can get along without each other. But thank goodness they aren’t, at least this winter. Praise the Lord and pass the checkbook.