The lights come up on the thin, nervous figure of Howard Shalwitz, knuckles to his mouth, body inclined doubtfully toward a red wooden chair across the rug from him. Playing Sparky Litman, the neurotic hero of "The Chinese Art of Placement," which opened Tuesday night at Woolly Mammoth, he has reason to be apprehensive: What if he makes the wrong choice about where to put the chair? "Where you place the chair," he informs us in utter seriousness, "makes a difference."

Actually, nothing is going to make a difference for poor Sparky, an upright, uptight, bow-tied loser who tells us he used to be a poet. "But the time came when I stopped being a poet, because I became normal." That's what he thinks. Sparky is the ur-nerd, doomed to hopeless loneliness. He should be little more than a pathetic bore, but in Shalwitz's exquisitely funny, painful performance, he's a heartbreaker.

Sparky is addressing us on the day he's decided to have a party and get his nice, new, normal life really rolling. Periodically he picks up a red phone and invites someone, but the short notice (the party is the next night) and the would-be host's obvious unraveling make for a lot of refusals. Seemingly undaunted, Sparky returns from each rejection to continue the story of his awful, wasted, humiliating--but, let's face it, amusing if you aren't the one living it--life.

With his wide, innocent eyes and hesitant smile, Shalwitz's Sparky is a diffident sufferer--an accident happening in front of you, but modestly, almost apologetically. As a poet, Sparky was in touch with his anger--after all, he explains, when you write poetry for people, "it's supposed to assault them."

But that's all behind him. Now he is going to have his furniture placed correctly to get that spiritual chi force going, suffusing his whole life with harmony.

The production is being staged on the nights "The Art Room" isn't playing and takes place, appropriately enough, on that show's skewed set. Designer Robin Stapley has given Sparky a gray, hexagonal Chinese rug, that red chair and a couple of humble sticks of furniture, and Shalwitz doesn't need any more. Jay A. Herzog's lighting is designed to subtly support Sparky's darkening mood but in execution jumps distractingly from level to level.

It's obvious from Sparky's first lines that the character has nowhere to head but smack into a wall of disappointment, and Stanley Rutherford's script is too long for the short emotional distance it travels. But under Lee Mikeska Gardner's nuanced direction, Shalwitz shows us a man going to Hell by inches, each inch containing a new torment. At the end, it's horrible to see that those eyes, once so soft and hopefully open, have gone dead as ashes.

The Chinese Art of Placement, by Stanley Rutherford. Directed by Lee Mikeska Gardner. At Woolly Mammoth Theatre through July 13. Call ProTix at 703-218-6500.

CAPTION: Interior redesign: Howard Shalwitz in "The Chinese Art of Placement."