A record-setting night for Lucian Freud at Christie’s set a positive tone as two days of major contemporary sales kicked off in London. The Wednesday night sale came at the midpoint of a week of winter auctions in the city, from which Sotheby’s and Christie’s expected to raise as much as $372 million.

The Impressionist and Modern sales Monday and Tuesday made for an up-and-down beginning to the week for the houses. Pablo Picasso, Chaim Soutine, and Yves Tanguy were the star artists at the Christie’s Impressionist sale. Christie’s set auction records for Soutine and Tanguy, as well as for two works on paper and a sculpture. While Christie’s sold 82% of its Impressionist and Modern works, some high-priced pictures by Pierre Bonnard, Edgar Degas, and Emile Bernard didn’t sell.

Soutine’s “Le Patissier de Cagnes” went to an unidentified telephone bidder for 5 million pounds ($9.3 million), including Christie’s commission, or about 25% above the top estimate. Christie’s second-most expensive picture was Tanguy’s “Les Derniers Jours,” which sold for 4 million pounds ($7.4 million) at the lineup of Surrealist pictures at the end of the sale. Completed in the United States, the 1944 oil painting shows monuments that seem to melt under a foggy sky. It’s one of only two large Tanguy works that isn’t in a museum. The winning bid was a third higher than the top estimate and a record for Tanguy.

One painting that Christie’s invested in before the sale didn’t find a buyer. Pierre Bonnard’s “Bord de Mer, Sous les Pins,” a 1921 beach scene in blue and orange, was valued at 2 million pounds ($3.72 million) to 3 million pounds ($5.6 million). The auctioneer said “Pass” at about 1.7 million pounds ($3.2 million). Christie’s will take a financial hit on the painting, as it was guaranteed: The house had bought all or part of the picture before the auction, according to the sale catalog.

On top of the hammer price, buyers pay a commission of 20% on the first 100,000 pounds and 12% on the rest of the value. Including commissions, Christie’s took in $76.3 million from its sale of Impressionist and Modern art on Monday. Sotheby’s Tuesday total of $69.8 million, meanwhile, skated above the low end of its estimated range of $64.2 million to $90.6 million.

Paintings by Pablo Picasso and Pierre Bonnard failed to sell at Sotheby’s, indicating buyers may be balking at prices demanded by sellers. They were two of the four most expensive works in a sale that raised 37.5 million pounds ($69.8 million).

Picasso’s “Femme au Chapeau,” a 1947 portrait of his lover Francoise Gilot, was valued as high as 3.5 million pounds ($6.5 million). Bonnard’s 1907 “Dans le Cabinet de Toilette” had a 3-million-pound ($5.6 million) top estimate. They drew scant bidding in a room overflowing with more than 500 people.

Sellers are unloading art after years of rising prices. Records set in the past year for artists from Egon Schiele to Picasso have boosted expectations of gain – and the auction houses’ estimates of value.

“My advice to clients is, don’t chase a picture” when the price is more than it’s worth, says London dealer James Roundell, who has been bidding for clients at the sales and losing more pictures than he won. “There are very few pictures you absolutely must have.”

“People are off their rockers if they pay these prices,” says gallery owner Acoris Andipa. “It will take them a long time to recover their money.”

Mr. Freud’s “Naked Portrait” of pregnant supermodel Kate Moss sold for a hammer price of 3.5 million pounds ($6.5 million) at a Christie’s International auction Wednesday night, momentarily setting a record for a work by the U.K. artist. That record was then broken by the sale for 3.7 million pounds ($6.8 million) of “Red Haired Man on a Chair,” a work Freud completed in 1963 that shows art student Tim Behrens crouched on a chair in a studio lined with white rags. Both paintings were bought by telephone bidders.

About 700 people crowded Christie’s auction rooms on King Street for its biggest-ever contemporary sale in the city. While the sale total isn’t in yet, Christie’s expected to raise $27.9 million to $40.9 million from the auction, which includes Warhol’s “Nine Multicolored Marilyns (Reversal Series),” made between 1979 and 1986.

The picture of Behrens was sold by the heirs of U.K. collector Erich Sommer. The Moss portrait, painted in 2002, was sold by its U.S.-based owner, who had bought it from New York’s Acquavella Galleries Inc., according to specialist Fernando Mignoni.

Sotheby’s will sell contemporary art tomorrow night on New Bond Street. On the cover of its catalog is Maurizio Cattelan’s 1997 sculpture, “Charlie Don’t Surf,” which is valued as high as 800,000 pounds ($1.4 million). It shows a child in a hooded coat at a school desk, his hands pinned down by pencils. Christie’s will sell more contemporary works tomorrow morning and will sell Impressionist and Modern works on paper tomorrow afternoon.