At the start of last night's "Top Chef Masters," at least one chef was starting to show the signs of the competition's wear and tear. There are only five chefs left: Anita Lo, Art "Food is Love" Smith, Hubert Keller, Michael Chiarello and Ricky Bayless.

   Michael Chiarello's giant burger

This week's episode chose to film on the day after Suzanne Tracht's departure, which is to say, after a long day of cooking and filming. Anita Lo, with a touch of a dark circles under her eyes, said that although (because?) she had won the previous night, she had had trouble sleeping. The day wasn't about to get any easier for her.

This week's Quickfire Challenge: make a gourmet burger and side dish.

Attention turns to Hubert Keller, who not only markets a $5,000 burger but has managed to actually sell a few. (Fleur de Lys' Fleurburger, if you're wondering, is a foie gras and truffle Kobe beef burger served with 1995 Chateau Petrus in crystal stemware.) Keller sheepishly admits that as a $5,000 burger flipper, he's seen as the man to beat. He turns to a Fleur de Lys favorite: a roquefort cheeseburger served with carmelized onions and rustic Yukon gold potatoes. The critics, which include Morgan Spurlock of "Super Size Me" fame, deem the cheese overpowering. (People like roquefort just fine at Fleur de Lys, Keller sniffs.)

The critics devour Michael Chiarello's super-sized 2.5 pound burger served across three buns, and suck up Rick Bayless's rib eye burger with queso fundido. They nitpick Bayless's choice to send out a guacamole trio, prompting the chef to question (from backstage) their ability to taste the differences between the guacamole styles. Art Smith's hoecake with fried green tomatillos and cole slaw goes over well with Southern boy Spurlock. Anita Lo's non-burger dish, however, meets with a cold reception. In a risky zig away from tradition, chef Lo sends out a cheddar cheese soup with mini-burgers, ketchup croutons and bacon fried onion rings. "This is a wish burger," Spurlock quips. "I wish there was a burger."

For the Elimination Challenge, the chefs have to prepare a lunch for actress Zooey Deschanel and her friends, but wait: there's no meat, fish, dairy, or eggs allowed. Or gluten. Or soy. Keller's face falls. Smith heaves a looooong sigh. "Wow," an increasingly deflated-looking Lo mutters. "Think of the things you love to cook... and just say no," Chiarello says of his take on gluten- and soy-free veganism. "It's all about no's. It's off-putting, to say the least." (Amen to that, Chef.)

The chefs divvy up the courses among themselves. Keller takes on the appetizer course: a white gazpacho of grapes, almond flour, cucumbers and vanilla oil, a timbale of asparagus and avocado and a beet salad. Keller narrowly averts disaster when ham-handed waiters drop two of his gazpacho shot glasses. "It's like heaven!," Zooey Deschanel exclaims after tasting the gazpacho. Later in the episode, Gael Greene said that guests were bowled over by the first course. "The vegans seemed so surprised," she said. "God knows what they get to eat."

For the second course, Lo whips up a grilled spicy eggplant with lentil salad cashew sauce and crispy shallot. (A version of it is on Annisa's menu, but with yogurt.) The reviews are mixed, with most guests calling out the oilyness of the eggplant. Greene notes that the dish, with lots of browns, looked sad. At the critics' table, Jay Rayner told Lo her dish was "big on taste but light on elegance."

Chiarello cleaned out Whole Foods' quinoa pasta for his third course, which he topped with salsa verde, pine nut gremolata and heirloom tomatoes. His wife was on a gluten-free diet for some time, he says, lending him a familiarity with quinoa. The vegans rave over the dish, since they had assumed pasta was gone forever from their diet. When Jay Rayner questions Chiarello over using a store-bought ingredient as his focus, the chef replies that Italians have a long history of "celebrating artisans."

Rick Bayless also had a family member with gluten-allergies; he seemed the least worried about the restrictions, noting Mexico's rich history of grains, beans and vegetables. His fresh sweet corn tamales with chili-braised beans and glazed mushrooms was an example of "Rick at his best" and "a true delight," the critics agreed.

Art Smith's strawberry-champagne soup with strawberry rice milk ice cream fared poorly. (Everyone loved his almond brittle, though.) The vegans had tasted better sweets, they said. The dish itself looked messy, Gael Greene gently chided Smith. And while Chiarello could justify his decision to base his dish around a store-bought item, Smith had no ready answer for choosing rice milk. "I wanted it right," Smith testily told Rayner. Smith later laments to the chefs, "I should've just made a strawberry sorbet and been done with it."

Probably. Smith loses the challenge. Lo squeaks past him by half a star. Chiarello takes the win. Keller and Bayless tie.

Next week: Cheftestants, meet Masters. A preview purports to show Season 4 chef Dale bullying Chiarello... but I'm onto you, trailers. I'll believe it when I see it.