Two weeks into Lupa, the newest tap dance of that Babbo duo, Pó’s “Molto” Mario Batali and Joe Bastianich (of the Felidia-Becco-Frico dynasty), their rustic take on a classic Roman trattoria is already jammed, already wonderful. And Village diners don’t seem to mind waiting. Witness the lineup tonight outside the sushi joint next door. (I find myself imagining a persistent Lupa queue braiding into that confusion: salami fans confronting uni-sushi and sashimi purists freaking out over lamb-brain ravioli.)

That’s star chef Jonathan Waxman hunched over a cell phone on Lupa’s sidewalk apron about to claim a seat at the bar for dinner. Yes, Waxman can’t get a table. Bushy-tailed young couples burst through the door where the pocket-size greeting space is already dense with standees.

Joe Bastianich doesn’t like it at all. “I don’t want to see a line on the sidewalk. It’s not Italian.” Last week, Lupa started taking reservations for the back room, but it’s first-come-first-seated up front. Now they’ve launched lunch, and cold food from the salumeria (delicatessen) is available all day to eat in or, till 5:30, to carry away. “The place looked bigger when we took it,” Bastianach says mournfully. Well, it’s going to get worse. Once diehard fans of Babbo’s earthy fare discover Lupa’s Roman variations at half the price and the house’s ambitious wine stash, they’ll be clustering outside, too. Happily for us, there are still vociferous detractors who loathe Babbo’s celebration of odd animal parts. I invite a nocturnal siren, my favorite trend-flasher, to dinner. “Why Lupa?” she asks suspiciously. For the she-wolf that nursed Romulus and Remus, I say. A bit of a she-wolf herself, she’ll enjoy the metaphor, I figure. “Oh, no,” she protests. “I don’t want that Addams Family food. Last time we went to Babbo, you ordered tongue salad, tripe, and beef cheeks.”

So here we are, a covey of adventurers (and one tenderfoot), having survived twenty minutes bunched like asparagus just inside the door, cozy now at a bare wood table, being tended by a polished waiter with stylish dreadlocks and a long white butcher’s coat. For all I know, Batali and Bastianich (partnered here with Jason Denton of the sandwich shop ‘ino) pumped sacks of cash into the place, but it looks untouched, vintage Village, with warm bare-brick walls and arches; a few hanging salamis; and a pair of monster slicing machines, machine-age sculpture.

The menu is short but the wine list is long, and we’re impressed to find a roving expert on hand, wine steward Robert Bohr, urging us to try the Rosso di Montalcino Caparzo ($38) and then decanting it. I watch him hunkering into a crouch to chat with a couple of grape nuts behind us. This is serious oenophiliac stuff in a spot where no entrée costs more than $15 and pastas start at $9. When was the last time you saw desserts for $5? It would be misleading for me to suggest that the kitchen is focused monomaniacally on tripe and muzzles and toenails. Silken prosciutto is offered with roasted figs and maybe a chunk or two of hard cheese. Calling it beet carpaccio just means the beet is raw and thinly sliced, deliciously mated with shaved celery and Pecorino. And the savory late-summer panzanella – tossed with the last of the righteous tomatoes, chunks of country bread, and, optionally, house-preserved tuna – shouldn’t frighten even the timid. Citrus-cured sardines with cracked wheat and the unctuous texture of octopus jelled into a kind of headcheese pleases our crowd.

It’s left to the waiter to translate the bits of Italian on the menu, scattered deliberately, I’m guessing, to create homey interaction. Smartly drilled, pulling no punches, he informs a questioner at our table that bucatini all’Amatriciana, Rome’s pasta classic, is a fat tubular spaghetti with a tomato sauce made of hog jowl. That’s all she needs to know. She cringes and orders the penne with broccoli, garlic, and toasted bread crumbs. “It’s just bacon by another name,” I mutter, ordering the bucatini myself – loving it this time but finding it muddy and bland a few nights later. Still, most of the pastas are fine, even fabulous: Linguine in a lightly tomatoed clam sauce. Lush ricotta gnocchi in a sensational sludge of sausage and fennel. Nero’s black tagliarini with spicy calamari stew. And one night’s special duck-stuffed agnolotti formed from first-rate pasta dough (not wonton skins). “Good grub,” my mate the Road Food Warrior pronounces. And that’s a compliment, definitely earned by a large chunk of moist baccalà in a luscious stubbly crumb crust on caramelized fennel and the remarkable fiorintina rib eye on piquant ribbons of sweet peppers with fried fingerlings on the side. “Don’t tell me what oxtails are,” begs one of my guests, rhapsodizing over the rich melting beef in a marvelous sauce with the faint sweetness of root vegetables.

Our group wants at least a taste of two or three cheeses to finish the wine, but we must have lemon-curd gelato too, as well as the fabulous house-made tartufo in a puddle of intense chocolate-hazelnut sauce and a delicate honey panna cotta (though the chopped figs in black pepper have an unpleasant aftertaste).

So far, lunch is not as frantic. Come for a Roman vegetable sampler, ricotta crostini with olive salad, half a dozen pastas, the piatto di giorno, and all sorts of panini – the hot oxtail sandwich with sweet onions seems irresistible to me. Once the kitchen is clicking under his chef de cuisine, Babbo veteran Mark Ladner, Batali tells me he will add a few signature favorites. Like the lamb-brain ravioli. “Brains, yes!” I can’t help encouraging him. I love brains. Almost nobody does them.

“That’s the kind of food that separates the men from the little girls,” he says.

“Wouldn’t it be more diplomatic to say ‘the adults from the spoiled brats’?” I suggest, not likely to be named to the Court of St. James’s myself.

“Okay, sure,” he says. “In the kitchen we call them the diners versus the spuds.”

Lupa, 170 Thompson Street (212-982-5089). Lunch Tuesday through Sunday, noon to 3 p.m.; salumeria service noon to 12:30 a.m.; dinner Tuesday through Sunday, 5:30 p.m. till 11:30 p.m. Closed Monday. A.E., D.C., M.C., V.