One-of-a-kind pieces by acclaimed artists Francis Bacon and Jeff Koons have sold at record-breaking prices, each raking in millions of dollars. The British painter's Three Studies of Lucian Freud is considered one of Bacon's greatest masterpieces, and an anonymous buyer is now the lucky owner of the painting, after topping bids at a New York auction. The triptych, which Bacon completed in 1969, went under the hammer for $142 million (£89 million) at Christie's, becoming the most expensive artwork ever sold at auction, surpassing a record set last year (12), when Edvard Munch's The Scream sold for $119.9 million (£74 million). Meanwhile, pop artist Koons' 12-foot-tall (3.6 meters) stainless steel balloon dog sculpture, sold for $58.4 million (£36.7 million), at Christie's on Tuesday night (12Nov13). It becomes the highest sum ever paid for a work by a living artist. Balloon Dog (Orange) is made to resemble the type of inflatable toy a clown would make at a children's party, and is one of five identical sculptures, with other primary colours in the series. Koons recently collaborated with Lady Gaga for her ARTPOP album cover, for which he created a nude sculpture of the Applause hitmaker in front of a blue sphere. On Sunday (10Nov13), the pair reunited at her artRave party in Brooklyn, New York, where she celebrated the release of her new record and also unveiled an installment of works by Koons, which included the 3D version of the ARTPOP cover sculpture.