Daniil Trifonov, the pianist who won the Tchaikovsky Competition in Moscow this year, looks very much like a 19th-century romantic poet. He has a lot of straight, soft brown hair in need of a trim; pale, translucent skin; and an arsenal of soulful expressions. When playing, he throws back his head, eyes heavenward, or arches over the keyboard until he looks like a 90-year-old, Dickensian hunchback picking notes from the instrument with a greedy, acquisitive glee, as if he were purloining cherries. And sometimes he bangs on the keys until the piano grows strident in protest.

In short, Trifonov is the physical embodiment of the stereotype of the Russian pianistic virtuoso. And he does a number of things one might find distracting, or annoying. It really doesn’t matter, though, because, as he showed on Saturday night, playing Tchaikovsky’s First Piano Concerto with Valery Gergiev and the Mariinsky Orchestra at George Mason University’s Center for the Arts, his playing is also freakishly brilliant.

That’s not to say it was always easy or even enjoyable to hear. It left me enervated and slightly disturbed. In some fast passages, his fingers produced a sound with a hypnotic, neurotic effect, an irresistible twitchiness that was all his own. Throughout the piece, routine patches or banging (was it a bad piano?) would yield to moments of startling precision that offered unexpected insights. Toward the end of the first movement, he played with such intensity that it seemed as if this moment was the greatest or most powerful thing that one could possibly experience. At that moment, for this 20-year-old pianist, it was.

The contrast of Chopin’s “Grande Valse Brillante,” which Trifonov offered as an encore, sealed the deal: This is a major artist in the making. For a musician so rife with mannerisms, Trifonov is shockingly unmannered. That is to say, he does many things that might read as precious, but he nonetheless conveys a sense of freshness rather than one of calculation. He had his way with the Chopin, so charmingly and artlessly that one didn’t mind being seduced by it. His rubato was a byproduct of the music rather than something inflicted on it, and the waltz’s repeating theme, which often feels dutiful and even hackneyed by its final iterations, sounded new, natural, self-evident and delightful each time he played it.

Small wonder that Gergiev — who headed the jury of this year’s Tchaikovsky Competition — has embraced Trifonov so wholly, bringing him on the U.S. tour with the Mariinsky and having him join the London Symphony Orchestra in the United Kingdom this fall (where, at one concert, a technical malfunction switched off the lights during the Tchaikovsky concerto, leaving Trifonov to offer some unplanned Chopin while Gergiev held a flashlight over the keys). To judge from the evidence on Saturday, their musical approaches are similar: the same manic quality, the same visceral impact, the same stretches of routine suddenly alleviated by an unexpected quirk or a flash of brilliance.

Gergiev, older and better-known, is also more obviously quirky, though his quirks have grown familiar to audiences around the world thanks to his ubiquitous, tireless presence on the podium and on recordings. His strength and weakness are the same: a headlong impetuosity that sweeps along everything in its path, music and musicians and listeners alike. He plunges into the music — on Saturday, the other piece on the program was Tchaikovsky’s Fifth Symphony — before the applause has subsided; he lets a movement trail off because his attention is already on the start of the next one; he lapses into stretches of mere routine at points when nothing particular happens to engage his interest. Details are of little consequence.

Balances were askew on Saturday, the low strings often outweighing the winds and even the brass in their tramping, marchlike figures; some passage work was mushy. Gesture is of more consequence than precision.

The result is music that seems to say something, or have done something, even if no one involved is given time to evaluate what that something might be. But that hardly matters: Gergiev is already off to his next gig — in this case, returning to Carnegie Hall with the orchestra in time for another all-Tchaikovsky concert Sunday afternoon. He left in his wake a performance that was messy, sloppy, headstrong, sometimes merely going through the motions, occasionally vivid. And his orchestra, knowing him well, its members’ evening wear creased from repeated wearings, responded with the slightly weary willingness and slurred speech of people who go to parties every night and do their best to lose themselves, over and over, in a bacchanalian frenzy, knowing the outlines of the dance without being quite sure what, on a given night, is likely to happen next.