Christie's International and Sotheby's start their high-profile contemporary art auctions tonight, fast on the heels of last week's seesaw Impressionist sales that prompted a 38 percent plunge in Sotheby's stock. A collection from the estate of New York dealer Allan Stone sells tonight at Christie's, stocked with rainbow-hued Wayne Thiebaud paintings, African tribal sculptures and a creamy 1967 Willem de Kooning painting that Stone hung over his mantel. The fresh material from an admired collector should start the week well, dealers said. The presale high estimate is $55 million. The rest of the week features a blend of powerful and pricey works by Andy Warhol, Jeff Koons, Francis Bacon and the newly trendy Chinese stars. The five-day series of sales is projected to tally as much as $1 billion. Christie's Impressionist and modern art auction last week tallied an impressive $473 million. Sotheby's, hobbled by inferior art and aggressive estimates, trailed at $331 million. "It's a wakeup call that you cannot sell B-minus material for A-plus prices," New York dealer Andrew Fabricant of Richard Gray Gallery said. "It's a day of reckoning, and it's going to stabilize things." Last week's $804 million total just missed the auctions' combined $818 million low estimate and fell far short of their $1.1 billion high estimate, suggesting the art market's exuberant rise may be slowing. Fashion-Driven Art Pricing for contemporary art is less predictable and more fashion-driven than for last week's Picassos and Monets. Peter Doig and Raqib Shaw are two artists who have recently shot to auction-block fame. "There is a lot of volatility in the contemporary market," private dealer Louise Eliasof said. "There's been a much larger appreciation in contemporary. The Impressionist masters are known. We don't change perspective about who is valuable." Even after Sotheby's disappointing sales last week and the breathtaking plunge of its share price, art experts predicted Sotheby's fortunes will improve this week. "Did Sotheby's do a better job in contemporary than Impressionist?"said New York private dealer Philippe Segalot. "Yes. The sale will be more successful." Segalot, who ran Christie's contemporary art department before becoming a dealer, said the U.S. contemporary art market continues to be strong, despite Wall Street's troubles. "The market is much wider than it has ever been," Segalot said. "In light of what happened last week, good works will perform extremely well and the others will not." Economist's View Economists are less optimistic. "I believe the financial factors are not going to go away," said William N. Goetzmann, director of the International Center for Finance at the Yale School of Management and a former director of the Denver Museum of Western Art."I'm guessing the art market is going to be paused or soft until the issue of the capital market is resolved." Goetzmann said the effect can be psychological. "It may not be that people don't have the money," he said. "It may be that they don't want to be seen buying excessively at this time." Christie's contemporary art sale tomorrow night, estimated at $271 million to $373 million, stars Warhol's 1963 turquoise "Liz (Colored Liz)," one of 13 versions of a red-lipped Elizabeth Taylor, estimated to sell for up to $35 million. Actor Hugh Grant paid $3.6 million for "Liz" at Sotheby's in New York six years ago. "Huge Increase" "That's a huge increase," Eliasof said. "We can't expect that to continue. It's not considered to be the best Liz." Christie's has promised Grant an undisclosed amount, regardless of the outcome of the sale. "The naysayers haven't seen this painting," said Christie's Brett Gorvy, co-head of the contemporary art department. "Everyone who has seen her has been blown away." He added that there may have been a backlash against Grant as well. "There is some antagonism against the seller," Gorvy said. People are upset that a celebrity with little art-world experience seems to be headed for huge profits, he said. Sotheby's Nov. 14 sale is expected to have an easier time with its marquee lots. An anonymous seller is offering Bacon's 1969 "Second Version of Study for Bullfight No. 1," depicting a swirling man and animal in an orange and mustard ring and estimated to sell for more than $35 million. Another highlight is Jeff Koons's shiny 3,500-pound sculpture "Hanging Heart (Magenta and Gold)," constructed in 1994-2006 and estimated to go for as much as $20 million. Phillips de Pury & Co. closes out the evening sales on Nov. 15, including works by Richard Prince, Damien Hirst and Yue Minjun. The sale is projected to total as much as $47.6 million.